Petticoat \Pet"ti*coat\, n. (Zo["o]l.) [Petty + coat.]

A loose under-garment worn by women, and covering the body below the waist.

Petticoat government, government by women, whether in politics or domestic affairs. [Colloq.]

Petticoat pipe (Locomotives), a short, flaring pipe surrounding the blast nozzle in the smoke box, to equalize the draft.

Source: Webster's Revised Unabridged Dictionary (1913)