fragile site [frăj′əl] n. A nonstaining gap at a specific point on a chromosome that usually involves both chromatids and always appears at exactly the same point on chromosomes of different cells from an individual or kindred. Liberaldictionary.com What It Really Means to Call Someone "Crude" Can You Translate These Famous Phrases From Emoji? These Are the Longest Words in English These Are the Saddest Phrases in English The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.