P

noun

the sixteenth letter of the alphabet.

1. (in tables of sports results) games played.
2. (on an automatic gear shift) park.
3. (on road signs and street plans) parking.
4. (in units of measurement) peta- (10¹⁵).

   27 PBq of radioactive material

5. poise (unit of viscosity).
6. Portugal (international vehicle registration).
7. proprietary.

symbol

the chemical element phosphorus.

1. page.

   see p 784

2. para-.

   p -xylene

3. penny or pence.

   a 5p coin

4. piano (softly).
5. (in units of measurement) pico- (10⁻¹²).

   a 220 pf capacitor

6. denoting electrons and orbitals possessing one unit of angular momentum.

   p-electrons

1. pressure.

   pV = nRT

2. probability.

   this difference was significant (p = 0.0008)

noun, symbol

the chemical element of atomic number 15, a poisonous, combustible non-metal which exists in two common allotropic forms, white phosphorus, a yellowish waxy solid which ignites spontaneously in air and glows in the dark, and red phosphorus, a less reactive form used in making matches.

late 17th century: from Latin, from Greek phōsphoros, from phōs ‘light’ + -phoros ‘-bringing’.