Enigma \E*nig"ma\, n.; pl. Enigmas. [L. aenigma, Gr. ?, fr. ? to speak darkly, fr. ? tale, fable.]

1. A dark, obscure, or inexplicable saying; a riddle; a statement, the hidden meaning of which is to be discovered or guessed.

A custom was among the ancients of proposing an enigma at festivals. --Pope.

2. An action, mode of action, or thing, which cannot be satisfactorily explained; a puzzle; as, his conduct is an enigma.

Source: Webster's Revised Unabridged Dictionary (1913)