unfit
No, "un-" is a prefix that is added to words to indicate a negation or reversal of the word's meaning. "Unbelievable" is a word itself, formed by adding the prefix "un-" to "believable."
Some words that use the prefix 'un' are:unableunbelievableunconsciousundeniableunendingunfurledungainlyunholyunimaginableunjustunknownunlovedunmeritedunnoticedunownedunprovenunquietunrestunsinkableuntidyunusedunvariedunwantedunexplained (OK, so I cheated a little)unyieldingunzip
un is the prefix of familiar so there is no prefix for an already prefixed word
unfit & unable
unique, unstoppable, understandable, anything starting with the prefix of un- such as: -uninteresting -unsolvable or the prefix uni- such as -unilateral
The prefix is un-. This prefix means not.
The prefix is un-
the prefix is un-
yes, un- is a prefix.
The prefix in unexceed is un-. This prefix means not.
persistent
See the related link for a list with OVER 1,500 words starting with the prefix IN.