RhymeZone: pissant definitions

Definitions of pissant:

noun: (dated outside dialects) An ant.
noun: (derogatory) An insignificant person.
noun: (derogatory) A person who adheres strictly to a rule or policy despite current circumstances.
noun: (derogatory) A person seemingly incapable of focusing on anything but the trivial, especially in the sense of trivial or irrelevant criticism.
adjective: (sometimes vulgar) Insignificant or unimportant.

(Definitions from Wiktionary)