p

from The American Heritage® Dictionary of the English Language, 5th Edition.

• abbreviation piano (musical direction)
• abbreviation proton
• noun The 16th letter of the modern English alphabet.
• noun Any of the speech sounds represented by the letter p.
• noun The 16th in a series.
• noun Something shaped like the letter P.
• noun A hypothesized textual source of certain portions of the Pentateuch that have a formulaic style, contain genealogical lists and descriptions of rituals, and use the name "Elohim" to refer to God.

from The Century Dictionary.

• noun An abbreviation of Philippine Islands.
• noun An abbreviation of Postal Order
• noun of Province of Ontario.
• noun An abbreviation of postscript; (theatrical) of prompt-side.
• An abbreviation of Post Adjutant.
• noun In ceramics, the abbreviation of ‘Paris granite,’ a trade-name.
• noun An abbreviation of Parish Priest;
• noun of the Latin Paler Patriæ, Father of his Country;
• noun [lowercase] in law, of per procuration, done by proxy;
• noun of the Latin punctum proximum, nearest point (namely, of accommodation to which the eye can adjust itself).
• noun An abbreviation of post-village.
• noun An abbreviation of Privy Councilor; of police constable.
• The sixteenth letter and twelfth consonant of the English alphabet, having a corresponding position in other alphabets.
• As a medieval numeral, 400; with a dash over it , 400,000.
• As a symbol: In chem., the symbol for phosphorus.
• In mathematics, the Greek capital II denotes a continued product.
• Thus, , for which Π (1 + m) is also written, denotes the product (1 + m) m (m − 1) … 3.2.1. The small Greek letter π denotes the ratio of the circumference to the diameter, or 3.14159265359 + . This notation was introduced by Euler. The other form of the Greek minuscule, ω%26, denotes in astronomy the longitude of the perihelion.
• An abbreviation: Of post in P. M., post meridiem, afternoon, and P. S., postscript.
• [lowercase] Of page (past participle standing for pages).
• [lowercase] In music, of piano, softly (past participle standing for pianissimo, very softly)
• [lowercase] In a ship's log-book, of passing showers.
• [lowercase] In zoology: Of partim. In dental formulas, same as pm. In ichthyology, of pectoral (fin). In echinoderms, of polyplacid.
• In medicine, of (Optic) papilla; pupil; pugillus, handful.
• noun An abbreviation of the Latin Populus Romanus, the Roman People;
• noun of Porto Rico;
• noun of the Latin punctum remotum, farthest point (namely, of accommodation to which the eye can adjust itself).
• noun An abbreviation of Pharmacopœia Dublinensis, Dublin Pharmacopœia.
• noun An abbreviation of Presiding Elder.
• noun An abbreviation of Paradise Lost
• noun of Poet Laureate
• noun [lowercase or cap.] in psychology, of partial limen.
• noun An abbreviation of the Latin Patres Conscripti, Conscript Fathers;
• noun of Perpetual Curate;
• noun [lowercase] of the Latin per centum, by the hundred;
• noun of the Latin pondus civile, avoirdupois weight;
• noun of Post Commander;
• noun [lowercase] of post- or postal-card;
• noun [lowercase] of the Latin post consulatum, after the consulship;
• noun of Principal Conductor;
• noun of Privy Council.
• noun An abbreviation of the Latin partes æquales, equal parts.
• noun An abbreviation: of post meridiem, ‘after noon or midday’ (also P. M., p. m.): frequently used as synonymous with afternoon or evening;