curtsy

To curtsy is to bend the knees and lower the body briefly as a mark of respect — the gesture women traditionally made to royalty, and dancers make at the end of a performance.

It is the female counterpart of a bow, and in Britain it survives almost entirely in encounters with the royal family, where it is customary rather than required. Ballet keeps it as the révérence at the end of a class. The spelling is curtsy or curtsey, both accepted, and the plural is curtsies. Note that the word is a worn-down form of courtesy, which makes it one of the neater etymologies in the language.