Modal \Mo"dal\, a. [Cf. F. modal. See Mode.]

1. Of or pertaining to a mode or mood; consisting in mode or form only; relating to form; having the form without the essence or reality. --Glanvill.

2. (Logic & Metaph.) Indicating, or pertaining to, some mode of conceiving existence, or of expressing thought.

Source: Webster's Revised Unabridged Dictionary (1913)