Also called romaine lettuce, cos, cos lettuce.a variety of lettuce, Lactuca sativa longifolia, having a cylindrical head of long, relatively loose leaves.
1907, from Fr. romaine (in laitue romaine, lit. "Roman lettuce"), from fem. of O.Fr. romain "Roman," from L. Romanus "Roman." Perhaps so called because of the lettuce's introduction into France (by Bureau de la Rivière, chamberlain of Charles V and VI) at the time of the Avignon papacy (1309-77).
[roh-meyn, ruh-] 
