late 14c., "not well known, obscure," from un- (1) "not" + famous (adj.). Also from late 14c. as "notably bad," a sense now in infamous.
Entries linking to unfamous
un- 1
prefix of negation, Old English un-, from Proto-Germanic *un- (source also of Old Saxon, Old Frisian, Old High German, German un-, Gothic un-, Dutch on-), from PIE *n- (source of Sanskrit a-, an- "not," Greek a-, an-, Old Irish an-, Latin in-), combining form of PIE root *ne- "not." Often euphemistic (such as untruth for "lie").
The most prolific of English prefixes, freely and widely used in Old English, where it forms more than 1,000 compounds. It underwent a mass extinction in early Middle English, but emerged with renewed vigor 16c. to form compounds with native and imported words. It disputes with Latin-derived cognate in- (1) the right to form the negation of certain words (indigestable/undigestable, etc.), and though both might be deployed in cooperation to indicate shades of meaning (unfamous/infamous), typically they are not.
It also makes words from phrases (such as uncalled-for, c. 1600; undreamed-of, 1630s; uncome-at-able, 1690s; unputdownable, 1947, of a book; un-in-one-breath-utterable, Ben Jonson; etc., but the habit is not restricted to un-; such as put-up-able-with, 1812). As a prefix in telegramese to replace not and save the cost of a word, it is attested by 1936.
famous adj.
late 14c., "celebrated in public report, renowned, well-known" also "notorious, infamous," from Anglo-French famous, Old French fameus (Modern French fameux), from Latin famosus "much talked of, renowned," often "infamous, notorious, of ill repute," from fama (from PIE root *bha- (2) "to speak, tell, say"). A native word for this was Old English namcuð, literally "name-known." Catch phrase famous last words in the humorous sense "remark likely to prove fatally wrong" is attested from 1921 (early lists of them include "Let's see if it's loaded ... We'll get across before the train comes ... Which one is the third rail? ... Light up, it can't explode").
infamous adj.
a 16c. merger of two Middle English words, with the form of infamous "not well-known" (early 15c.) and the sense of infamis (late 14c.), "of ill repute, famous for badness." Infamous is from Medieval Latin infamosus, from in- "not, opposite of" (see in- (1)) + Latin famosus "celebrated" (see famous). Infamis is from Latin infamis "of ill fame" (see infamy).
Meaning "causing infamy" is from 1550s. As a legal term, "disqualified from certain rights of citizens because of conviction for certain crimes" (late 14c.). The neutral fameless (in the sense original to infamous) is recorded from 1590s. Related: Infamously.