p- prefix 1. short for para-16 2. (Chemistry) short for para-16 Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014P, p (pi) n., pl. Ps P’s, ps p’s. 1. the 16th letter of the English alphabet, a consonant. 2. any spoken sound represented by this letter. 3. something shaped like a P. 4. a written or printed representation of the letter P or p. P 1. Genetics. parental. 2. (as a rating of student performance) passing. 3. Electronics. plate. 4. Protestant. P Symbol. 1. the 16th in order or in a series. 2. phosphorus. 3. Physics. a. power. b. pressure. c. proton. d. poise 2. 4. proline. p 1. penny; pence. 2. Music. softly. [