infamous:  The negative connotations of infamous go back a long way – to the word’s source, in fact, Latin infāmis. This did not mean simply ‘not well known’; the prefix in- denoted positively ‘bad’, and so infāmis signified ‘of ill repute’. In post-classical times infāmis became infamōsus, which passed into English as infamous. => famous
"of ill repute," late 14c., from Medieval Latin infamosus, from Latin in- "not, opposite of" (see in- (1)) + famosus "celebrated" (see famous). Meaning influenced by Latin infamis "of ill fame" (see infamy). As a legal term, "disqualified from certain rights of citizens in consequence of conviction of certain crimes" (late 14c.). The neutral fameless is recorded from 1590s. Related: Infamously.