Ruga
(
ῥυτίς). Literally, a wrinkle; whence, the worm of a screw
(Pliny ,
Pliny H. N. xviii. 74; and Cochlea), and a small, irregular crease or fold in a piece of drapery,
contradistinguished from
sinus, a deep and loose one, and from
contabulatio, a straight and regular one (Pliny ,
Pliny H. N. xxxv. 34; Macrob.
Sat. ii. 9).