The term 'kind of lettuce' refers to four different types of lettuce: Cos (3 letters), ICEBERG (7 letters), Bibb (4 letters), and ROMAINE (7 letters). Cos lettuce, also known as ROMAINE lettuce, is a variety of lettuce that has long, dark green leaves and a crunchy texture. ICEBERG lettuce is a crisp, mild-flavored lettuce with a light green color. Bibb lettuce, also known as butterhead lettuce, is a type of lettuce with soft, loose leaves and a sweet flavor. Finally, ROMAINE lettuce is a variety of lettuce with long, dark green leaves and a crunchy texture. All four types of lettuce are popular ingredients in salads and other dishes.