Glossary 625 



Ferment: Living organisms, such as yeast or bacteria, that cause the 



breaking up of organic matter ; a chemical substance, such as the 



enzymes in the body, which aids digestion of food. 

 Fermentation: The decomposition, or breaking up, of organic matter by 



living organisms, such as yeasts and bacteria. Frequently accompanied 



by the formation of bubbles of escaping gas. The "raising" of bread 



dough and the formation of vinegar from cider are examples. 

 Fertilizer: Any substance containing plant food used to enrich the soil. 

 Fibers: The thread-like structures of plant and animal tissue. 

 Fibrin (fi'brin) : A solid, white substance which forms when blood is 



clotted. 

 Field magnets: U-shaped magnets or electromagnets used to provide 



the magnetic field within which rotates the armature of a magneto, 



dynamo, or electric motor. 

 Filament (fll'd-ment) : A thread-like fiber. 



Filter: A device for straining any undesirable matter from a liquid. 

 Fire escape: A stairway or chute by which people may escape from a 



building in case of fire. 



Fire extinguisher: A device for putting out a fire. 

 Fire hazard: Something dangerous on account of its liability to catch 



or cause fire. 

 Fireless cooker: A box in which hot food is placed to cook without the 



further use of fire. 

 Firing: The exposure of bricks or pottery to intense heat in order to 



harden or glaze them. 



Fission (fish'wn) : Reproduction by dividing. 

 Flexor muscle (flek'sor) : Any muscle which bends a limb. 

 Floodlight: A powerful lamp which brilliantly illuminates a wide area. 

 Flora (flo'rd) : The native plants which grow within a certain region. 

 Flue: A passage or pipe to carry away flame and smoke. An air passage 



for ventilating. 



Fluid: Any gaseous or liquid substance. 

 Focus (fo'kws) : To bring to a central point. 

 Fog: Water vapor condensed in the air near the earth into small drops 



not heavy enough to fall. 



Food: Material for the growth, repair or energizing of any living body. 

 Foot pound: The amount of work done in lifting a pound avoirdupois 



through a distance of one foot. 

 Force: The use of energy in the 'effort to do work. Energy which tends 



to produce motion or a change of motion in a body. 

 Forestry: The science of cultivating and caring for forests. 

 Formaldehyde (for-mal'de-hid) : A gaseous compound having a sharp 



penetrating odor ; used as a disinfectant and preservative. 

 Fossil: A rock form of a plant or an animal which in past ages left a 



mold of itself which became filled with rock-forming material. 

 Fracture: The breaking of a bone in the body. 

 Frequency: Rate of occurrence, as of light waves. 

 Friction: Resistance encountered when a surface is rubbed over another 



surface. 

 Frigid zone: The part of the earth between either polar circle and its 



pole. 



Frost: Minute ice crystals formed in place of dew at 32 F. or below. 

 Fruit: The seed-bearing part of a plant. 

 Frying: Cooking in hot fat. 

 Fuel: Any material used to provide heat by burning. 



