early 14c., "befitting one of gentle rank, as of good family," from gentle + -ly (2). Meaning "quietly, softly, without rudeness, gradually" is from 1550s.
a gently sloping terrain
he talked gently to the injured animal
gentle
gentleman
gentlemanly
gentleness
gentlewoman
gently
gentrification
gentrify
gentry
*genu-
genuflect