1630s, "give life to," from en- (1) "make, put in" + live for life + -en (1). Meaning "make lively or cheerful" is from 1690s. Related: Enlivened; enlivening. Enlive in same sense is from 1590s. A noun, enlivement, is recorded from 1877.
enlighten
enlightened
enlightenment
enlist
enlistment
enliven
enmesh
enmity
ennead
ennoble
ennui