P

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Related to P cells: Parvocellular pathway, Magnocellular pathway

P,

16th letter of the alphabetalphabet
[Gr. alpha-beta, like Eng. ABC], system of writing, theoretically having a one-for-one relation between character (or letter) and phoneme (see phonetics). Few alphabets have achieved the ideal exactness.
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, representing the voiceless bilabial stop. It corresponds to Greek pi, but in form it looks like Greek rho (see RR,
18th letter of the alphabet, corresponding to Greek rho. When in Latin alphabets the letters for p and r became similar in appearance, the rho form (P; which at first was used for the r sound) was restricted to the p
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). For the technical use of P in higher criticism, see Old TestamentOld Testament,
Christian name for the Hebrew Bible, which serves as the first division of the Christian Bible (see New Testament). The designations "Old" and "New" seem to have been adopted after c.A.D.
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. In chemistry P is the symbol of the element phosphorusphosphorus
[Gr.,=light-bearing], nonmetallic chemical element; symbol P; at. no. 15; at. wt. 30.97376; m.p. 44.1°C;; b.p. about 280°C;; sp. gr. 1.82 at 20°C;; valence −3, +3, or +5.
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P

(science and technology)
(chemistry)
(fluid mechanics)

P

1. On drawings, abbr. for page.
2. Abbr. for pole.

P

pharmacy only: used to label medicines that can be obtained without a prescription, but only at a shop at which there is a pharmacist