Pn. the 16th letter of the Roman alphabet ; Pn. a multivalent nonmetallic element of the nitrogen family that occurs commonly in inorganic phosphate rocks and as organic phosphates in all living cells ; is highly reactive and occurs in several allotropic forms ; p-n junctionn. the junction between a p-type semiconductor and an n-type semiconductor ; p-n-p transistorn. a junction transistor having an n-type semiconductor between a p-type semiconductor that serves as an emitter and a p-type semiconductor that serves as a collector ; p-type semiconductorn. a semiconductor in which electrical conduction is due chiefly to the movement of positive holes ; P. G. Wodehousen. English writer known for his humorous novels and stories (1881-1975) ; P. P. von Mausern. German arms manufacturer and inventor of a repeating rifle and pistol (1838-1914) ; P. T. Barnumn. United States showman who popularized the circus (1810-1891) ; p.a.adv. by the year ; every year (usually with reference to a sum of money paid or received) ; P.A.n. an electronic amplification system used as a communication system in public areas ; P.A. systemn. an electronic amplification system used as a communication system in public areas ; P.E.n. the mechanical energy that a body has by virtue of its position ; stored energy ; p.m.adj. after noon ; P.M.adv. between noon and midnight ; P.O.n. a noncommissioned officer in the Navy or Coast Guard with a rank comparable to sergeant in the Army ;
