1540s, "expression of respect," a variant of courtesy (q.v.). Specific meaning "a bending the knee and lowering the body as a gesture of respect" is from 1570s. Originally not exclusively feminine.
curtsy (v.)
"make a curtsy," 1550s, from curtsy (n.). Related: Curtsied; curtsying.
She curtsied when she shook the Queen's hand
curtail
curtain
curtal
curtilage
curtsey
curtsy
curvaceous
curvature
curve
curvilinear
curvity