1610s, "overtaken by night" from staying too late or being delayed, past-participle adjective from belate "to make late, detain," from be- + late. Sense of "coming past due, behind date" is from 1660s. Related: Belatedly; belatedness.
a belated birthday card
bel
bel canto
bel paese
belabor
belabour
belated
belay
belch
beldam
beleaguer
beleave