Noun | 1. | ![]() butterhead lettuce - lettuce with relatively soft leaves in a loose head; easily broken or bruised crisphead lettuce, iceberg lettuce, iceberg - lettuce with crisp tightly packed light-green leaves in a firm head; "iceberg is still the most popular lettuce" genus Lactuca, Lactuca - an herb with milky juice: lettuce; prickly lettuce lettuce - any of various plants of the genus Lactuca |