_Fahrenheit._ A thermometric scale, in common household use, but employed for scientific purposes far less frequently than the Centigrade scale. The boiling point of water is 212 degrees and the freezing point is 32 degrees above zero. _Fair._ As used by the American Weather Bureau, without rain, snow, or hail. _Feces._ Excrement. _Fecundate._ Impregnate, fertilize, make fruitful. _Female._ Bearing fruit or offspring, pistillate. _Ferment._ To cause an organic substance to change or to work (used of organic substances), because of the activity of yeast, or of certain other living organisms or substances derived from them. _Filament._ The part of the stamen that supports the anther. The conductor in an incandescent electric light. _Fish._ A member of a class of vertebrate and cold-blooded animals having gills and usually fins and scales. _Flocculus._ A mass in the atmosphere of the sun resembling wool or clouds. _Florescence._ The time or condition of flowering. _Flower._ The reproductive organ in a plant which contains one or more pistils or stamens or both, and typically a corolla and calyx. To flower: to blossom or produce flowers. _Fluid._ Moving readily. The fluids include the liquids, the gases, perhaps the ether of space. _Fluorescence._ The colored light produced in some transparent bodies by the action of ultra-violet rays. The property some substances have of emitting light when exposed to certain rays. _Fluorine._ A gaseous element. Symbol: F. _Focus._ The point at which rays meet after reflection or refraction. Converging-point. _Force._ That which changes or tends to change the motion of a body upon which it acts. _Foreconscious._ Mental processes of which we are aware only under special conditions. Of a nature between conscious and unconscious. _Forensic._ Used in law-courts. _Formula._ A symbolic statement, as in mathematics or chemistry. _Fossil._ Something left of an animal or a plant which lived in a former geological age. _Freeze._ To change from a liquid to a solid, especially by removing heat. _Friction._ The resistance which one body encounters in rubbing against another. _Fruit._ A ripened ovary together with any parts of the flower that may be attached to it. _Fulcrum._ The point where a lever is supported or turns. _Function._ A quantity related to another in such a way that a change in one involves a change in the other. _Functional._ Having a use. Of a disease, not affecting the structure of an organ, or of the organ which is supposed to be diseased. It is doubtful if there can be a disease which does not change the structure of some organ. _Fundamental notes._ The notes resulting when a piano wire vibrates as a whole. The lowest notes of chords. _Fungus._ Plural: fungi. A cryptogamous (flowerless) plant without chlorophyll. A morbid growth. _Fuse._ To change, usually by adding heat, from solid to liquid form. _Gadolinium._ A metallic element. Symbol: Gd.