. "off the wall Adjective (comparative more off-the-wall, superlative most off-the-wall)(idiomatic) Wildly unconventional; bizarre; absurd.What kind of a harebrained, off-the-wall idea is that?She is a very off-the-wall character.(idiomatic) Greatly inappropriate.His behaviour today is off-the-wall.Origin Perhaps from baseball or other games played with a ball, alluding to unpredictable bounces.Adjec" . . .