diacritical 
diacritical mark, point, or sign Diacritical 
mark, point, or sign, a dot, line, or other mark added 
or put adjacent to a letter or sign in order to distinguish 
it from another of similar form, or to give it a different 
phonetic value, or to indicate some particular accent, 
tone, stress, or emphasis, as in schemes for the trans- 
literation of foreign languages into Roman letters, or for 
indicating the exact pronunciation of words, as in the 
scheme of marking pronunciation used in this dictionary. 
Thus, the marks attached to a ill the forma a, a, a, are di- 
acritical marks, or diacritics. So in the angular German 
running-hand the letter u (u) is written thus, ft, to distin- 
guish it from n (n) ; and the dot over the i, formerly used 
also over y, has a like office. Diacritical marks and points 
are regularly used as a part of the alphabetical systems 
of many languages. 
From "f," in the Icclandick alphabet, "v" is distin- 
guished only by a diacritical point. 
Johnson, Grammar of the English Tongue. 
Any system of diacritical marks which aims at being 
universal must necessarily be either cumbrous, incom- 
plete, or inconsistent. Isaac Taylor, The Alphabet, I.,Pref. 
diact (di'akt), a. A contracted form of diactine. 
diactinal (dl-ak'ti-nal), a. [< diactine + -al.] 
Same as diactine. 
diactine (dl-ak'tin), a. [< Gr. Si-, two-, + d/cri'f 
(OKTIV-), a ray.] Having two rays ; sharp-point- 
ed at each end, as a sponge-spicule of the mo- 
naxon,biradiate, or rhabdus type. W. J. Sollas. 
diactinic (di-ak-tin'ik), a. [<Gr. Std, through, 
+ o/v-rif (OKTIV-), a ray : see actinic.] Capable 
of transmitting the actinic or chemical rays of 
the sun. 
diadelph (di'a-delf), n. [< NL. "diadelplms : 
see diadelphous.~] In bot., a plant the stamens 
of which are united into two bundles or sets 
by their filaments. 
Diadelphia (di-a-del'fi-ii), n. pi. [NL., < *di- 
adel/thus : see diadelphous.] The name given 
by Linna3us to his seventeenth class of plants. 
It consists chiefly of leguminous genera. 
diadelphian (di-a-del'fi-au), a. [< NL. Diadel- 
phia, q. y.] Same as diadelphous. 
diadelphic (di-a-del'fik), a. [As diadelph-ous 
+ -ic.] Being one of a group of two. 
diadelphite (di-a-del'fit). n. [< Gr. 61-, two-, 
+ aticA^df, brother, + -ite%.] A manganese ar- 
seniate occurring in red rhombohedral crystals 
at Nordmark in Sweden. The name has reference to 
its close relation to synadelphite and other similar min- 
erals from the same locality. Also called hematolite. 
diadelphous (di-a-del'fus), a. [< NL. *dia- 
delpltuis, < Gr. 61-, two-, + d<5f/l0of, brother.] 
In bot., having stamens 
united in two sets by their 
filaments, the sets being 
equal or unequal ; group- 
ed together in two sets: 
as, diadelphous stamens. 
In papilionaceous flowers, out of ten stamens 
nine are often united, while one (the posterior 
one) is free. Also diadelpliian. 
diadem (di'a-dem), n. [< ME. diademe (= D. 
diadeem = G! Dan. Sw. diadem), < OF. diademe, 
F. diacUme = 
Sp. Pg. It. dia- 
dema, < L. dia- 
dema, < Gr. iid- 
6r//ia, a band or 
fillet, < fna&Kiv, 
bind round, < 
6id, through, + 
deiv, bind, tie.] 
1. Anciently, a 
head-band or fillet worn by kings as a badge 
of royalty. It was made of silk, linen, or wool, and 
encircled the temples and forehead, the ends being tied 
behind, so as to fall on the neck. It was originally white 
and plain, but was later embroidered with gold or set with 
pearls or precious stones, and little by little increased in 
richness until it was developed into the modern crown. 
The hair, instead of being arranged in spiral curls over 
the brow and temples, is twined as if round a concealed 
diadem. A. S. Murray, Greek Sculpture, I. 108. 
2. Anything worn on the head as a mark or 
badge of royalty; a crown. 
A crown, 
Golden in show, is but a wreath of thorns ; 
Brings dangers, troubles, cares, and sleepless nights 
To him who wears the regal diadem. 
Milton, P. R., ii. 461. 
Mont Blanc is the monarch of mountains ; 
They crown'd him long ago 
On a throne of rocks, in a robe of clouds, 
With a diadem of snow. Byron, Manfred, i. 1. 
3. Figuratively, supreme power ; sovereignty. 
What more can I expect while David lives ? 
All but his kingly diadem he gives. 
Srydeu, Abs. and Achit. 
4. In her., one of the arches which rise from 
the rim or circle of a crown, and support the 
mound or globe at the top. 5. In goal., a 
certain monkey, Cercopithecus diadematus, 
Parthian Diadem, a. Jeweled Diadem 
of Constantine. ( From ancient coins. ) 
1588 
diadem (dl'a-dem), v. t. [< ME. diademen, in 
pp. used as "adj., after L. diadematus, diadem- 
ed; from the noun.] To adorn with o^ as if 
with a diadem ; crown. 
And Dauid shal be diademyd, and daunten alle cure 
enemyes. Piers Plowman (C), iv. 444. 
Not so, when diadem'd with rays divine, 
Touch'd with the flame that breaks from Virtue's shrine. 
Pope, Epil. to Satires, ii. 232. 
Diadema (dl-a-de'ma), n. [NL., < L. diadema, 
a diadem: see diadem.'] 1. A genus of Crusta- 
cea. Schumacher, 1817. 
2. The typical genus 
of sea-urchins of the 
family Diadematidce. 
D. mexicanus and D. 
setosum- are examples. 
J. E. Gray, 1825. 3. 
A genus of nymphalid 
butterflies. Boisduval, 
1832. 4. A genus of 
MolluSCd. Pease, 1868. Diadema sctomm. 
diadematid(di-a-dem'- 
a-tid), n. A sea-urchin of the family Diade- 
matidfe. 
Diadematidae (di"a-de-mat'i-de), n.pl. [NL., 
< Diadema(t-) + -Idee.'] A family of desmos- 
tichous or regular sea-urchins, order Endocy- 
clica, represented by the genus Diadema, hav- 
ing a thin test, very long, hollow, fragile ver- 
ticillate spines, crenulate perforate tubercles, 
and notched peristome. 
diademed (di'a-demd), p. a. [< diadem + -ed?.] 
In her., surrounded or surmounted by a circle, 
like a halo or glory: applied to the eagle of 
the Holy Koman Empire, the two heads of 
which were anciently diademed to distinguish 
them from the similar bearings of other princes, 
which were simply crowned. 
diadem-spider (dTa-dem-spi'der), n. A name 
of Eprira diadema,'tiie common garden-spider: 
so called from its markings. See cut under 
cross-spider. 
diadexis (di-a-dek'sis), n. [NL., < Gr. SiaSeS-is, 
a taking from, succession, relief, < 6ia6exeo6at, 
take from, succeed to, < Sia, through, + dexeaSai, 
take, receive.] In pathol., a transformation of 
a disease into another, differing from the for- 
mer in both its nature and its seat. Dunglison. 
Diadochi (di-ad'o-kl), n. pi. [NL., < Gr. 6id- 
6oxoi, pi. of fiiadoxof, a successor, prop, adj., 
succeeding, < titaScxcaffat, succeed to, receive 
from another: see diadexis."] The Macedonian 
generals of Alexander the Great, who, after his 
death in 323 B. c., divided his empire. 
Since the time of Alexander many Jews have been led 
to settle beyond Palestine, either with commercial objects 
or attracted by the privileges conferred by the diadochi 
on the inhabitants of the cities they founded. 
Encyc. Brit., XVIII. 760. 
Diadochian (di-a-do'ki-an), a. [< Diadochi + 
-i'an.] Relating to the Diadochi. 
Sear the marble steps were various remains belonging 
to a monument of small dimensions and lavish Diadochian 
ornamentation. 
J. T. Clarke, Rep. of Assos Expedition, 1881, p. 40. 
diadochite (di-ad'o-kit), n. [< Gr. didfoxof, a 
successor (see Diadochi) (in allusion to its re- 
lation to the arseuiate pitticite or iron sinter), + 
-jfe 2 .] A hydrous iron phosphate with iron sul- 
phate occurring in stalactitic forms of a yel- 
lowish-brown color and resinous luster. 
Diadophis (di-ad'o-fis), n. [NL. (Baird and 
Girard, 1853), < Gr! iiM(ima), a band or fillet, + 
oij>i(, a snake.] A genus of Colubridce, having the 
head distinct, the body slender with smooth 
scales, the postabdominal scutella bifid, the sub- 
caudals all divided, the cephalic plates normal, 
with a well-developed loral, 2 postorbitals, 2 
anteorbitals, and 2 nasals, between which lat- 
ter is the nostril. The best-known species is D. punc- 
talus, the ring-necked snake, found in many parts of the 
United States, a very common and pretty snake, quite 
harmless, of small size, and dark-green color above and 
yellowish below, with a yellowish ring round the neck. 
There are several others. 
diadromt (di'a-drom), n. [< Gr. StaSpoa/], did- 
(Spojuof, a running through. < titaSpafieiv, run 
through, < Sid, through, + 6pa.jj.ftv, run, second 
aor. associated with Tpi%nv, run.] 1. A course 
or passing. 2. A vibration ; the time in which 
the vibration of a pendulum is performed. 
A philosophical foot [is] one third of a pendulum, whose 
diadroms, in the latitude of forty-five degrees, are equal 
to one second of time, or a sixtieth of a minute. Locke. 
diaeresis, . See dieresis. 
diaeretic, a. See dieretic. 
diageotropic (dl-a-je-o-trop'ik), a. [< Gr. Std, 
through, across, '4- yij, the earth, + TATTOO, a 
diagonal 
turning (< Tpfaeiv, turn), + -ic.] In bot., grow- 
ing horizontally or transversely to the direction 
of gravitation. 
diageotropism(di // a-ie-ot'ro-pizm), n. [Asdia- 
geotrop-ic + -ism.]" In bot.', transverse geotro- 
pism; a turning in a direction at right angles 
to that of gravitation. Darwin. 
diaglyph (di'a-glif), n. [< Gr. SmyUjeoi, carve 
through, carve in intaglio, < Sid, through, + 
fAv<t>cw, carve : see glyph.] A sculptured or 
engraved production in which the figures are 
sunk below the general surface ; an intaglio. 
diaglyphic (di-a-glif ' ik), a. [< diaglyph + -ic.] 
Pertaining to sculpture, engraving, etc., in 
which the design is sunk into the general sur- 
face. 
diagnose (di-ag-nos'), v. t. ; pret. and pp. di- 
agnosed, ppr. diagnosing. [* diagnos-is.] In 
pathol., zoo!., and bot., to determine the diag- 
nosis of; ascertain, as a disease, from its symp- 
toms; distinguish ; discriminate; diagnosticate. 
diagnosis (di-ag-no'sis), . ; pi. diagnoses (-sez). 
[= F. diagnose = Sp. Pg. diagnosis = It. di- 
agnosi, < NL. diagnosis, < Gr. Siayvucif, a distin- 
guishing, < SiayiyvaoKciv, distinguish, discern, < 
aid, between, + yiyvixmeiv (tf *} v u), know, = E. 
know 1 , q. y. Cf. gnosis, gnostic, etc.] Scien- 
tific discrimination of any kind ; a short dis- 
tinctive description, as of a plant. Specifically 
() In pathol., the recognition of a disease from its symp- 
toms; the determination of the nature of a diseased con- 
dition, (b) In zool. and bot., a specific characterization; 
a brief, precise, correct, and exclusively pertinent defini- 
tion. In this sense diagnosis is nearly synonymous with 
definition : both differ from description in omitting details 
or non-essential particulars ; but definition may include 
points equally applicable to some other object, the par- 
ticular combination of points given making it a diagnosis. 
Differential diagnosis, the distinction between two 
more or less similar diseases or objects of natural history. 
diagnost (di'ag-nost), n. [< diagnost-ic.] One 
who diagnoses. 
diagnostic (dl-ag-nos'tik), a. and n. [=F. dia- 
gnostique = Sp. diagnostico = Pg. It. diagnos- 
tico, < Gr. SiayvooTiKOf, able to distinguish, < 
iidyvuaic, a distinguishing : see diagnosis.] I. 
a. Of or pertaining to diagnosis ; determining 
a diagnosis ; indicating the nature ; constitut- 
ing a ground of discrimination. 
The great diagnostic point between amnesic and ataxic 
aphasia is, that in the former the patient can always ar- 
ticulate the forgotten word when it is suggested to him ; 
in the latter, no prompting or assistance can enable him 
to enunciate the proper sound. Encyc. Brit., II. 171. 
II. n. 1. In pathol., a symptom of value in 
diagnosis. Diagnostics are of two kinds: the adjunct, 
or such as are common to several diseases ; and the spe- 
cial or pathognmnonic, which distinguish a certain dis- 
ease from all others. 
2. In zool. and bot., a term or phrase which 
constitutes a diagnosis ; a definition or charac- 
terization. 
diagnosticate (di-ag-nos'ti-kat), t 1 . t. ; pret. and 
pp. diagnosticated, ppr. diagnosticating. [< di- 
agnostic + -ate 2 .] To make or give a diagnosis 
of; discriminate or characterize, as one species 
or disease from another ; diagnose. 
Woman as well as man can sell goods, plan buildings, 
make statues, resolve nebulee, discover elements, diag- 
nosticate diseases, construct philosophies, write epics. 
Boardman, Creative Week, p. 229. 
diagnostician (dFag-nos-tish'an), n. [< diag- 
nostic + -Jan.] One skilled in diagnosis. 
The injured tissue which puts forth an immediate effort 
at repair is a diagnostician and a doctor on a minute scale. 
Mind in Nature, I. 51. 
diagnostics (dl-ag-nos'tiks), . [PI. of diag- 
nostic: see -ics.] That department of medicine 
which relates to the study of the symptoms as 
indicating the disease ; symptomatology. 
But Radcliffe, who, with coarse manners and little book 
learning, had raised himself to the first practice in London 
chiefly by his rare skill in diagnostics, uttered the more 
alarming words small-pox. Macaulay, Hist. Eng., xx. 
diagometer (dl-a-gom'e-ter), n. [Irreg. < Gr. 
Sidyeiv, conduct (\ did, through, + dyetv, lead), 
+ fiirpov, a measure.] A kind of electroscope, 
consisting of a dry pile and a magnetized nee- 
dle for an indicator, used for ascertaining the 
conducting power of different bodies . It was first 
employed by Rousseau to detect adulterations in olive-oil, 
which is said to have less conducting power than other 
fixed oils. 
diagonal (d!-ag'o-nal), a. and n. [= F. Sp. 
Pg. diagonal = ft. diaqonalc = D. diayoiiual = 
G. Dan. Sw. diagonal, ^L. di- 
agonalis, < diagonios, < Gr. 
diay&v-tof, from angle to an- 
gle, diagonal, < Sid, through, 
across, + jww'a, a corner, 
angle.] I. a. 1. In gcom., 
extending, as a line, from Diagonal of a Rectangle. 
