MEANING: noun: A rogue; an adventurer.

ETYMOLOGY: From Spanish picaro (rogue). Earliest documented use: 1622. Also see picaresque and picaroon.

PICRO- - prefix meaning one trillionth ( 10 ^ -12 )

PI, CLARO - What does a Spanish mathematician call the ratio of the circumference of a circle to its diameter?

PICA PRO - someone with ingests bizarre substances, like ice or lead paint chips or dirt, for a living