_Synthetic._ Produced outside the living organism. Artificial. Making more complex. _Tantalum._ A metallic element. Symbol: Ta. _Tellurium._ A rare non-metallic element. Symbol: Te. _Temperature._ Degree, not total amount, of heat. _Tendon._ A cord or band of tissue connecting a muscle with another part. _Terbium._ A metallic element. Symbol: Tb. _Tertiary._ Relating to the third in a series, as of organic compounds. Relating to the geological period before the Quaternary. _Thallium._ A metallic element. Symbol: Tl. _Thallophyte._ One of a phylum (Thallophyta) of simple plants including fungi and lichens. _Thallus._ A simple plant body without root, stem, or leaves. _Theology._ The “science” of religion, especially Christian religion, and of God, according to lexicographers and other writers. Newman argues very well that if there is a miracle-working God whom we can understand by studying the Bible and the traditions of the Catholic Church, then theology is an essential branch of science. I do not see how any man who grants his premises can fail to agree with him. _Theory._ A generalization which has not been absolutely proved. Sometimes one that stands between a hypothesis and a law, not so certain as the latter, more certain than the former. However, phrases continue, often when their meaning has changed, and it seems that “Theory of Evolution” may be used when the Fundamentalists have already accepted it. Also scientific principles in general. Sound theory and proper practice are not enemies. _Thermo-._ In compounds, heat, temperature. As, thermodynamics: the science of the relation between heat and mechanical work. _Thorax._ The part of the trunk between the neck and the tail or the abdomen. _Tin._ A metallic element. Symbol: Sn. Most objects which we say, in ordinary language, are made of tin, are made of tin plate. _Tincture._ The alcoholic solution of a drug. _Titanium._ A metallic element. Symbol: Ti. _Triassic._ Relating to the geological division between the Permian and the Jurassic. _Typhoon._ A violent hurricane. _Ulotrichi._ The wooly-haired races of mankind. _Ultra-violet rays._ Invisible rays of the spectrum beyond the violet rays. _Ungulate._ One of a group (Ungulata) of mammals having horns and hoofs. _Uranium._ A metallic element. Symbol: U. Uranium is radioactive. _Vacuum._ A space which does not contain matter. A vacuum, in a laboratory, is a space which has been exhausted of matter to a great extent; for scientists have not been able to produce a perfect vacuum. _Value._ The amount of other commodities for which a thing can be exchanged in the open market. _Valve._ The membranous part of an organ which permits the flow of a liquid in one direction only. _Vanadium._ A metallic element. Symbol: V. _Vapor._ A gas, especially one which exists at ordinary temperatures in liquid or solid form. _Velocity._ Rate of motion. _Vertebrate._ Having a spinal column, belonging to the class of Vertebrata.