pico-
/ˈpaɪkəʊ/combining form
1- (used in units of measurement) denoting a factor of 10-12皮（可）; 微微; 万亿分之一：
picosecond.
1.1
- very small表示“极小的”：
picornavirus.
词源
from Spanish pico, literally 'beak, peak, little bit'.