1. Highest in rank, authority, character, importance, or degree; most considerable or important; chief; main; as, the principal officers of a Government; the principal men of a state; the principal productions of a country; the principal arguments in a case. "Wisdom is the principal thing." (Prov. Iv. 7)

2. Of or pertaining to a prince; princely. Principal axis. See Axis of a curve, under Axis. Principal axes of a quadric, a plane passing through the optical axis of a crystal.

Origin: F, from L. Principalis. See Prince.

(01 Mar 1998)