Source : Webster's Revised Unabridged Dictionary (1913)

Malapropos \Mal*ap"ro*pos`\, a. & adv. [F. mal [`a] propos; mal
   evil + [`a] propos to the purpose.]
   Unseasonable or unseasonably; unsuitable or unsuitably.

Source : WordNet®

malapropos
     adj : of an inappropriate or incorrectly applied nature [ant: {apropos}]
     adv : at an inconvenient time; "he arrived inopportunely just as
           we sat down for dinner"; "she answered malapropos"
           [syn: {inopportunely}] [ant: {opportunely}]