on 
I thocht if it [a door] sulcl be open, it wad be a fine thing 
(or me, to baud fowk ohn seen me. But it was verra Ill- 
bred to you, mem, I ken, to come throu' your yainl (An 
speirt leave. (?. MacDonald, Robert falconer, xvii. 
[The spelling ohn in the last quotation simulates the G. 
equivalent oftfte.] 
on- 1 . [< ME. on-, < AS. on-, an- = OS. an-, etc.; 
the prep, (and adv.) on used as a prefix: see 
on*.] A prefix of Anglo-Saxon origin, being 
the preposition or adverb on used as a prefix, 
with its usual meanings. See examples below. 
on- 2 t. An obsolete form of the prefix an- 2 as in 
answer, etc. 
on- 3 . An obsolete or dialectal form of the nega- 
tive prefix -!. 
on- 4 . An obsolete or dialectal form of the pre- 
fix J(- 2 before verbs. 
onager (on'a-jer), n. [L., also onagrus, < Gr. 
dvaypof, a wild ass, MGr. a kind of catapult, < 
ivof, an ass, + ayp6f, wild, of the fields : see 
Agrion.~] 1. A wild ass, Kquus hemippus orE. 
Onager (EqtlHS 
onager, inhabiting the steppes of central Asia. 
See dziggetai. 2. A war-engine for throwing 
stones, used in Europe in the middle ages. 
Onagra (o-na'gra), n. [NL. (Tournefort, 1700), 
< Gr. bvdypa, a dubious reading for oivaypa, a 
plant (< oivof, wine, + aypa, a hunting), same 
as olvoBiipa.*;, a certain plant : see CEnotliera.] In 
hot., same as (Enotliera. 
Onagraceae (.on-a-gra'se-e), n. pi. [NL. (Lind- 
ley, 1845), < Onagra + -ace<e,.~\ See Onagrariea;. 
Onagrarieae (o-na-gra-ri'e-e), n. pi. [NL. (A. L. 
de Jussieu, 1804), < Onagra + -aria + -ere."] The 
evening-primrose family, an order of dicotyle- 
donous polypetalous plants, of the cohort Myr- 
tales, typified by the genus (Enothera, and char- 
acterized by the two- to four-celled ovary co- 
herent with the valvate calyx, the two to four 
petals, one to eight stamens, and undivided 
style. It includes about 330 species, of 23 genera, scat- 
tered through all temperate regions. They are odorless 
herbs, rarely woody, bearing thin opposite or alternate 
undivided leaves, and axillary or raeemed flowers often 
of showy colors. The more euphonious form, Onagra- 
cecK, employed by Lindley, is still much in use. See cut 
under (Enothera. 
onant, onanet, adv. Middle English forms of 
anon. 
onanism (6'uan-izm), n. [< Onan (Gen. xxxviii. 
9) + -ism.'] Gratification of the sexual appetite 
in an unnatural way. 
onanist (6'nan-ist), . [< onan(ism) + -ist.'] 
A person addicted to or guilty of onanism. 
onanistic (o-na-nis'tik), a. [< onanist + -c.] 
Of, pertaining to, or caused by onanism. 
onbraidt, . t. [ME. var. of abra^d.] To up- 
braid. 
once 1 (wuns), adv. and conj. [< ME. ones, onis, 
< AS. anes (= OS. enes, eines = OFries. enes, enis, 
ense, ens = D.eens = MLG. eincst, ens, ins = OHG. 
einest, MHG. einest, einst, G. einst), once, ad- 
verbial gen. of an, one : see one. For the term. 
-ce, prop, -es, see -ce 1 .] I. adv. 1. Onetime. 
As he offer'd himself once for us, so he received once of 
us in Abraham, and in that place the typical acknowledg- 
ment of our Redemption. Milton, Touching Hirelings. 
2. One and the same time : usually with at: as, 
they all cried out at once. See phrases below. 
3. At one time in the past; formerly. 
I took once 52 Sturgeons at a draught, at another 88. 
Capt. John Smith, Works, I. 117. 
Anxiety and disease had already done its work upon his 
once hardy constitution. Prescott, Ferd. and Isa., ii. 25. 
4. At some future time ; some time or other. 
The wisdom of God thought fit to acquaint David with 
that court which we shall once govern. Bp. Hall. 
5. At anytime; in any contingency; on any 
occasion; under any circumstances; ever. 
Also whan it rcynethe ones in the Somer, in the Lond of 
Egipt, thanne is alle the Contree fulle of grete Jlyrs. 
Mandeville, Travels, p. 49. 
4110 
Dangers are no more light, if once they seem light. 
Bacon, Delays. 
Who this heir is he does not once tell us. 
Locke, Civil Government. 
6. Without delay; immediately: often merely 
expletive : as, John, come here once. [Local, 
Pennsylvania.] 7t. Once for all. 
That is once, mother. Dryden, Maiden Queen, IT. 1. 
All at once, not gradually; suddenly; precipitately. At 
once (a) At one and the same time ; simultaneously : as, 
they all rose at once. When followed by another clause be- 
ginning with and, at once is equivalent to both : as, at once 
a. soldier and a poet ; the performance is fitted at once to 
instruct and to delight. 
No more the youth shall join his consort's side, 
At once a virgin, and at once a bride ! 
Pope, Iliad, xi. 314. 
He wished to be at once a favourite at Court and, popular 
with the multitude. Macaulay, Lord Bacon. 
(6) Immediately ; forthwith ; without delay. 
I have resolved, therefore, to fix you at once in a noble 
independence. Sheridan, The Rivals, ii. 1. 
Every once In a while. See everyi.'Foi once, on one 
occasion ; once only ; exceptionally : often with the sense 
of 'at last' : as, you have succeeded for once. 
Put the absurd impossible case for once. 
Browning, Ring and Book, I. 149. 
Once and again. See again. Once for all, for one time 
only, and never again ; at this one time and for all time. 
You must excuse me, sir, if I tell you, once for all, that 
in this point I cannot obey you. 
Sheridan, The Rivals, ii. 1. 
Once In a way, once and no more ; on one particular oc- 
casion ; on rare occasions. [Colloq.] 
Mr. Munder . . . seemed, for once in a way, to be at a 
loss for an answer. W. CoUim, Dead Secret, iv. 4. 
II. conj. When at any time; whenever; as 
soon as. [Recent; a specially British use.] 
A great future awaits the Caucasus, onceita magnificent 
resources become known to Europe. 
Contemporary Jtev., L. 274. 
once 2 t, An obsolete form of ounce%. 
Onchidiidae (ong-ki-di'i-de), n. pi. [NL., < 
Chichidium + -icke.'] A family of ditrematous 
geophilous pulmoniferous gastropods, without 
a developed shell, and with a thick, more or 
less tuberculate mantle, the jaw smooth or but 
slightly ribbed, and the dentition differentiated 
into a central tooth, tricuspid lateral teeth, and 
marginal teeth with quadrate base. A British 
species is 0. celticum. Another species, Peronia tonyana, 
has the whole back covered with eyes, besides the proper 
pair borne upon the ends of the tentacles. 
Onchidinm (ong-kid'i-um), n. [NL., prop. Onci- 
dium (which is used also in another sense) : see 
Oncidium.] The typical genus of Oncliidiida\ 
Onchidorididae (ong"ki-do-rid'i-de), n. j>l. 
[NL., < Onehidoris (-dorid-)'+ -idas.] A family 
of nudibranchiate gastropods, typified by the 
genus Onehidoris. The body is convex, the mantle is 
large and margins the foot, the dorsal tentacles are lami- 
nate, the branchise surround the vent and are not retrac- 
tile, the lingual membrane is narrow, and the teeth are in 
two principal longitudinal series and sometimes two small- 
er series. They are found on both sides of the Atlantic. 
Onehidoris (ong-kid'o-ris), n. [NL.. < Gr. 
o^Kof, the barb of an arrow, + iopif, a sacrifi- 
cial knife. Cf. Doris."] The typical genus of 
Onchidorididw. 
Oncidieae (on-si-di'e-e), n. pi. [NL. (Ben- 
tham and Hooker, 1883), < Oncidium + -ea.~\ 
A subtribe of orchids of the tribe Vandea', typi- 
fied by the genus Oncidium, and characterized 
as epiphytes with the flower-stalk rising from 
the base of a pseudo-bulb or a fascicle of a few 
fleshy non-plicate leaves. It includes about 40 
genera. 
Oncidium (ou-sid'i-um), n. [NL. (Swartz, 1800), 
so called from the shape of the labellum; < 
Gr. oyxof, a hook 
or bend, + dim. 
-iStov."] A genus of 
orchidsof the tribe 
Vandew, type of 
the subtribe Onci- 
diece, and known 
by the free.spread- 
ing sepals, and 
spurless lip free 
from the short 
two-auricled col- 
umn. There are over 
250 species, natives of 
America from Brazil 
and Bolivia to the 
West Indies and Mex- 
ico. They are epi- 
phytes, usually with 
pseudo-bulbs,very few 
lei 
leaves, and loose ra- 
cemes Of showy yel- Oncidium Pafilia. 
lowish flowers. This 
is an extremely rich and varied genus. One of the best- 
known species is 0. Papilio, the butterfly-plant, with flow- 
onde 
ers of butterfly form borne singly at the end of long stalks. 
0. altigsimum is said to produce a raceme 13 feet long, with 
as many as 2,000 flowers. O. Sprucei has the name of ar- 
madillo's-tail, on account of its long round leaves, charac- 
teristic of one section of the genus. 0. Carthayinciise is 
named spread^ayle orchid. 
oncin (ou'siu), n. [< OF. oncin, oucin, < LL. 
iincinus, a hook, barb, < L. wneus, < Gr. iiynof, a 
hook, barb.] A weapon resembling a hook or 
a martel-de-fer with one point. 
oncograph (ong'ko-graf), K. jX Gr. 6;/.of, bulk, 
mass, volume, + ypafeev, write.] A form of 
plethysinograph for recording the variations 
in the volume of a body, such as the spleen or 
kidney. 
oncology (ong-kol'o-ji), n. [< Gr. oj/wf, bulk, 
mass (> oyKOvaBm, swell, > bynufia, a swelling), + 
-Xoyia, (At-yeiv, speak: see -ology.~] The sum of 
scientific knowledge concerning tumors. 
oncome (on'kum), . [< ME. (income, an attack ; 
< OM 1 + come. Cf. ancome, income.] 1. A fall 
of rain or snow. [Prov. Eng.] 2. The com- 
mencement or initial stages of a business, es- 
pecially of one that requires great exertion, 
as in making an attack. 3. An attack, as of 
disease. 
This woman had acquired a considerable reputation 
among the ignorant by the pretended cures which she 
performed, especially in on-cvmes, as the Scotch call them, 
or mysterious diseases which baffle the regular physician. 
Scott, Bride of Lammermoor, xxxi. 
oncometerCong-kom'e-ter),". [< Gr. ojieof, bulk, 
mass, + utrpov, measure.] An instrument de- 
signed to measure variations in size in the kid- 
'ney, spleen, and other organs ; the part of the 
oncograph which is applied to the organ to be 
measured. 
on-coming (on'kum"ing), H. Approach. 
Those confused murmurs which we try to call morbid, 
and strive against as if they were the oncoming of numb- 
ness. George Eliot, Middlemarch, xx. 
on-coming (on'kum "ing), <i. Approaching; 
nearing. 
Oncorhynchus (ong-ko-ring'kus), n. [NL., < 
Gr. oy/cof, a hook, barb, + t>iryxf, a snout.] A 
fenus of anadromous American and Asiatic 
almonida', inhabiting the North Pacific ocean : 
so called from the hooked jaws of the spent 
males; the king-salmon. These salmon are of great 
size and economic importance. There are 5 well-deter- 
mined species : the<ininnat or king-salmon proper, O. qvin- 
nat or chamcha (see quinnat) ; the blue-backed salmon, 0. 
nerka; the silver salmon, 0. Mxutch; the dog-salmon, 0. 
keta; and the humpbacked salmon, 0. gortmecha. The fe- 
males and young and other variations of these have given 
rise to some 35 nominal species, referred to several differ- 
ent genera. See salmon. 
oncosimeter (oug-ko-sim'e-ter), n. [< Gr. 6j- 
Koovf, swelling (< ojAwoftw, swell, < ojvtof, bulk, 
mass), + /itrpov, a measure.] An instrument 
devised by Wrightson for determining the den- 
sity of a molten metal. A ball of the same or other 
metal is immersed in the liquid and supported by a deli- 
cate spiral spring connected with a scale ; by this means 
the relation between the weight of the ball and that of 
the liquid displaced (its buoyancy) can be determined both 
when the ball is cold and as its volume changes with rise 
of temperature ; the corresponding changes in the spring 
may be recorded by a pencil on a revolving drum. 
Oncosperma(ong-k6-sper'ma),. [NL.(Blume, 
1835); so called perhaps from the protuberant 
remains of the stigma on one side of the seed ; 
< Gr. oyKOf, bulk, mass, lump, -t- airfpfia, seed.] 
A genus of palms of the tribe Arecece, type of 
the subtribe Oncospermea;, and known by the 
parietal ovule and erect anthers. There are 5 or 
6 species, all from tropical Asia. They are low trees, set 
with long straight black thorns, and bearing terminal pin- 
nately divided leaves, small flowers and fruit, the stam- 
inate and pistillate flowers on different branches of the 
same spadix. See nibunff. 
oncotomy (oug-kot'o-mi), n. [Also onkotomy; 
<. Gr. 6y/a>c, a mass (tumor), + -rofiia, < rt^veiv, 
ra/ixlv, cut.] In surg., the incision into, or the 
excision of, a tumor. 
Oncotylidae(ong-ko-til'i-de),!.^. [NL. (Doug- 
las and Scott, 1865), < Oncotylii* + -iila:~\ A 
family of Heteroptera , named from the genus 
Oncotylus. It includes 7 genera of wide distribution, 
containing elongate, parallel-sided, or somewhat suboval 
bugs of the superfamily Capsina. 
Oncotylus (ong-kot'i-lus), n. [NL. (Fieber, 
1858), < Gr. oj'Kof , a hook, + rW.of , a knob, lump.] 
A genus of plant-bugs of the family Cajixitltr, 
or giving name to the Oncotylida; occurring in 
Europe and North America. 
ondatra (on-dat'ra), . [Amer. Ind. (?).] 1. 
The musquash or muskrat of North America, 
Fiber zibethims. 2. [cap.] [NL.] Same as Fi- 
berV, 2. Lacepede. 
ondeif, n. [ME., also ande, < AS. tinda, zeal, 
indignation, auger, malice, hatred, envy, = OS. 
undo, wrath, = MLG. ande = OHG. tuiin. innl<>. 
