<B>psychotogen, </B>noun.<DL COMPACT><DD> a drug that produces a psychotic state; psychotogenic drug. <BR> <I>Ex. A psychologist at Phipps Clinic foresees a future in which some hallucinogens, more precisely those described as psychotogens, will be used in ways that will benefit the functioning of the human brain (Johns Hopkins Journal).</I> </DL>
<B>psychotogenic, </B>adjective.<DL COMPACT><DD> inducing or causing a psychotic state. <BR> <I>Ex. a psychotogenic drug. The effects of Vietnamese marijuana were sometimes surprisingly similar to those induced by hallucinogenic and psychotogenic agents such as L.S.D., mescaline and other so-called mind-expanders that have ... proved harmful to the body and central nervous system of humans (London Times).</I> </DL>
<A NAME="psychotomimetic">
<B>psychotomimetic, </B>adjective, noun.<DL COMPACT><DD><I>adj. </I> producing a state resembling or symptomatic of psychosis. <BR> <I>Ex. They were conducting experiments with LSD and other psychotomimetic drugs (Harper's).</I> <DD><I>noun </I> a psychotomimetic drug or substance. <BR> <I>Ex. LSD ... was the first of the "modern" psychotomimetics (Hannah Steinberg).</I> <DD> Also, <B>psychomimetic.</B> adv. <B>psychotomimetically.</B> </DL>
<A NAME="psychotoxic">
<B>psychotoxic, </B>adjective.<DL COMPACT><DD> harmful to the mind or personality; capable of producing mental disorder. <BR> <I>Ex. He asked for laws to control the production and sale of such drugs as barbiturates, amphetamines, and other psychotoxic drugs (New York Times).</I> </DL>
<A NAME="psychotoxicity">
<B>psychotoxicity, </B>noun.<DL COMPACT><DD> psychotoxic quality or condition. </DL>
<A NAME="psychotropic">
<B>psychotropic, </B>adjective, noun.<DL COMPACT><DD><I>adj. </I> affecting the mental processes. <BR> <I>Ex. a psychotropic drug.</I> <DD><I>noun </I> a psychotropic drug or substance. <BR> <I>Ex. ... possession of marijuana, hashish, or other psychotropics (Science News).</I> </DL>
<A NAME="psychozoic">
<B>psychozoic, </B>adjective.<DL COMPACT><DD> of or belonging to the geological period of living creatures having minds or intelligence. <BR> <I>Ex. Our interest, ... is in planets that may have intelligent life now, not in planets ... whose "psychozoic era" has passed (Scientific American).</I> </DL>
<A NAME="psychro">
<B>psychro-,</B><DL COMPACT><DD> (combining form.) cold; coldness, as in <BR> <I>Ex. psychrometer, psychrotolerant.</I> </DL>
<A NAME="psychrometer">
<B>psychrometer, </B>noun.<DL COMPACT><DD> an instrument for measuring the relative humidity of the air, consisting of two thermometers, a dry-bulb and a wet-bulb thermometer. The difference between their temperature readings is a measure of the relative humidity. </DL>
<A NAME="psychrometric">
<B>psychrometric, </B>adjective.<DL COMPACT><DD> of or having to do with a psychrometer. </DL>
<A NAME="psychrometry">
<B>psychrometry, </B>noun.<DL COMPACT><DD> the branch of physics that deals with the measurement of the relative humidity in the air. </DL>
<A NAME="psychrophile">
<B>psychrophile, </B>noun.<DL COMPACT><DD> a psychrophilic microorganism. </DL>
<A NAME="psychrophilic">
<B>psychrophilic, </B>adjective.<DL COMPACT><DD> requiring low temperatures for development. <BR> <I>Ex. psychrophilic bacteria. Psychrophilic microorganisms have been defined as organisms with the ability to grow well at 0 degrees C (J. L. Ingraham).</I> </DL>
<A NAME="psychrotolerant">
<B>psychrotolerant, </B>adjective.<DL COMPACT><DD> able to endure cold. <BR> <I>Ex. Slime is caused by cold resistant, or psychrotolerant, bacteria which are not a health hazard but which produce an objectionable smell and change the colour of the meat (Science Journal).</I> </DL>
<A NAME="psylla">
<B>psylla, </B>noun.<DL COMPACT><DD> any one of a group of insects that suck the juices of plants and are serious pests of fruit trees, such as the pear psylla. </DL>
<A NAME="psyllid">
<B>psyllid, </B>adjective.<DL COMPACT><DD> of or belonging to the psyllas. <BR> <I>Ex. a psyllid bug.</I> </DL>
<A NAME="psyllium">
<B>psyllium, </B>noun.<DL COMPACT><DD> a plantain whose flealike seeds are used as a laxative; fleawort. </DL>
<A NAME="psyops">
<B>psyops, </B>noun pl.<DL COMPACT><DD> (Informal.) operations used in psychological warfare. <BR> <I>Ex. [He] also oversees the mission's psyops ... such as the printing of propaganda leaflets (New York Times).</I> </DL>
<B>PTA</B> (no periods) or <B>P.T.A.,</B><DL COMPACT><DD> Parent-Teacher Association (an organization of the parents and teachers of a school, established to improve the environment of the community for children, especially by supporting the activities of the school). </DL>
<A NAME="ptadeficiency">
<B>PTA deficiency,</B><DL COMPACT><DD> a form of hemophilia caused by a deficiency in blood plasma of one of the factors necessary for blood clotting. </DL>
<A NAME="ptah">
<B>Ptah, </B>noun.<DL COMPACT><DD> (in ancient Egypt) the chief god of Memphis, father of men and gods and ruler of the world. </DL>
<A NAME="ptarmigan">
<B>ptarmigan, </B>noun, pl. <B>-gans</B> or (collectively) <B>-gan.</B><DL COMPACT><DD> any one of several kinds of grouse that have feathered feet and are found in mountainous and cold regions. The plumage of most varieties is brownish in summer, white in winter. </DL>
<A NAME="ptboat">
<B>PT boat,</B><DL COMPACT><DD> a small, fast motorboat which carries torpedoes, depth bombs, and light antiaircraft armament. </DL>
<A NAME="ptc">
<B>PTC</B> (no periods),<DL COMPACT><DD> phenylthiocarbamide. </DL>
<A NAME="ptcdeficiency">
<B>PTC deficiency,</B> =Christmas disease.</DL>
<A NAME="pte">
<B>Pte.,</B><DL COMPACT><DD> Private (in the British Army). <BR> <I>Ex. And you with the Etruscan look not Pte. Maecenas by any chance? (Listener).</I> </DL>
<A NAME="pteranodon">
<B>pteranodon, </B>noun.<DL COMPACT><DD> a large, toothless pterodactyl with a hornlike crest projecting from its head. </DL>
<A NAME="pteridine">
<B>pteridine, </B>noun.<DL COMPACT><DD> any one of various compounds derived from pigments in the wings of butterflies, characterized by a fused pyrazine and pyrimidine ring system. </DL>
<A NAME="pteridological">
<B>pteridological, </B>adjective.<DL COMPACT><DD> having to dowith pteridology. </DL>
<A NAME="pteridologist">
<B>pteridologist, </B>noun.<DL COMPACT><DD> an expert in the study of ferns. </DL>
<A NAME="pteridology">
<B>pteridology, </B>noun.<DL COMPACT><DD> the branch of botany that deals with ferns. </DL>
<A NAME="pteridophyte">
<B>pteridophyte, </B>noun.<DL COMPACT><DD> any one of a division of seedless and flowerless plants, having roots, stems, and leaves. Ferns, horsetails, and club mosses are pteridophytes. <BR> <I>Ex. The tissues of seed plants and pteridophytes are all derived from a fertilized egg (zygote) which has undergone repeated divisions (Heber W. Youngken).</I> </DL>
<A NAME="pteridophytic">
<B>pteridophytic, </B>adjective.<DL COMPACT><DD> of or having to do with pteridophytes. </DL>
<B>pteridosperm, </B>noun.<DL COMPACT><DD> any one of a group of fossil plants having the external aspect of ferns, but bearing true seeds; seed fern. <BR> <I>Ex. Fernlike pteridosperms are the earliest to start protecting their seeds (New Scientist).</I> </DL>
<A NAME="pterin">
<B>pterin, </B>noun.<DL COMPACT><DD> a pigment or other compound containing a ring system such as that of pteridine. Folic acid and xanthopterin are pterins. </DL>
<A NAME="pterodactyl">
<B>pterodactyl, </B>noun.<DL COMPACT><DD> an extinct flying reptile that had wings somewhat like those of a bat. There were various kinds. The wings consisted of a strong, featherless membrane stretching from the elongated fourth digit of each foreleg to the body. Pterodactyls existed during the Jurassic and Cretaceous periods. </DL>
<A NAME="pterodactyloid">
<B>pterodactyloid, </B>adjective.<DL COMPACT><DD> having the form or characteristics of a pterodactyl. </DL>
<A NAME="pterodactylous">
<B>pterodactylous, </B>adjective.<DL COMPACT><DD> of or like a pterodactyl. </DL>
<A NAME="pteron">
<B>pteron, </B>noun.<DL COMPACT><DD> (Architecture.) a side row of columns in a classical temple. </DL>
<A NAME="pteropod">
<B>pteropod, </B>adjective, noun.<DL COMPACT><DD><I>adj. </I> of or belonging to a group of mollusks with lateral portions of the foot expanded into winglike lobes used in swimming. <DD><I>noun </I> a pteropod mollusk. </DL>
<B>pteropodous, </B>adjective.<DL COMPACT><DD><B> 1. </B><B>=pteropod.</B> <DD><B> 2. </B>characteristic of a pteropod. </DL>
<A NAME="pterosaur">
<B>pterosaur, </B>noun.<DL COMPACT><DD> an extinct flying reptile; pterodactyl. <BR> <I>Ex. On the land were the dinosaurs, in the sea the ichthyosaurs ... in the air the pterosaurs (A. Franklin Shull).</I> </DL>
<A NAME="pterosaurian">
<B>pterosaurian, </B>adjective, noun.<DL COMPACT><DD><I>adj. </I> <B>1. </B>of or belonging to the same order as the pterodactyl. <DD><B> 2. </B>like a pterodactyl. <DD><I>noun </I> <B>=pterodactyl.</B> </DL>
<A NAME="pterygium">
<B>pterygium, </B>noun, pl. <B>-iums,</B> <B>-ia.</B><DL COMPACT><DD> a triangular patch of thickened conjunctiva growing over the cornea that obscures vision. </DL>
<A NAME="pterygoid">
<B>pterygoid, </B>adjective, noun.<DL COMPACT><DD><I>adj. </I> <B>1. </B><B>=winglike.</B> <DD><B> 2. </B>of or having to do with either of two processes of the sphenoid bone. <DD><I>noun </I> a pterygoid muscle, nerve, or other related part. </DL>
