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1.
When a person smokes enough marijuana to feel its effects, but not enough to alter competence at regular daily tasks or create a lasting low after the effects have worn off.

Becoming functionally high is a skill that comes naturally for some, and for others takes a long time to develop and master.
Person 1: I just got some killer bud from a friend of mine. Wanna smoke?

Person 2: Ok, but I have work in an hour. I guess I'll go in functionally high.
by DJAlexxander September 07, 2011