pico-

1. One-trillionth (10 ^-12): picosecond.
2. Very small: picornavirus.

[Spanish pico, beak, small quantity, from Latin beccus, beak, of Celtic origin (influenced by Spanish picar, to prick).]

[SI: a quantifier meaning × 10^-12] Smaller than nano-; used in the same rather loose connotative way as nano- and micro-. This usage is not yet common in the way nano- and micro- are, but should be instantly recognizable to any hacker. See also quantifiers, micro-.

[Etymology: Span: ‘small’] Symbol p-. (Metric) The 10^-12 multiplier, e.g. 1 picogram = 1 pg = 10^-12 g.

1. One-trillionth (10^-12): picogram.
2. Very small: picornavirus.