means Excessively active, energetic, or excited — keyed up past the point of calm.

from From Greek 'hyper,' meaning 'over, above, beyond, exceeding.' It's the natural counterpart to 'hypo' ('under, beneath') and a likely cousin of Latin 'super,' both tracing back to a Proto-Indo-European root for 'over.' For centuries it lived quietly as a scientific and medical prefix (hyperactive, hypertension), but in casual 20th-century speech it broke loose to stand alone as an adjective for anyone bouncing off the walls.