Bibb lettuce (b?b)n. A kind of lettuce forming a small, loose head and having tender, dark green leaves.[After Jack Bibb, 19th-century American vegetable grower.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.Bibb? let?tuce (b?b) n. a variety of lettuce having a small tapering head and light-green leaves. [1960?65] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.