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."