butterhead I. \ˈ ̷ ̷ ̷ ̷ˌ ̷ ̷\adjective orbutterheading\ˈ ̷ ̷ ̷ ̷ˌ ̷ ̷ ̷ ̷\ of lettuce: forming a substantial but soft head of delicate-flavored tender leaves that tend to bleach at the heart to a clear yellow II. \ˈ ̷ ̷ ̷ ̷ ˌ ̷ ̷ \noun : butter lettuce herein