infamous: [14] 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[infamous etymology, infamous origin, 英语词源]