Definition of "Behind" :

noun: the fleshy part of the human body that you sit on

adjective: having the lower score or lagging position in a contest

"Behind by two points."

adverb: in or to or toward the rear

"He followed behind."

adverb: remaining in a place or condition that has been left or departed from

"When he died he left much unfinished work behind."

adverb: in debt

"He fell behind with his mortgage payments."

adverb: in or into an inferior position

"Fell behind in his studies."

adverb: of timepieces

"My watch is running behind."