Okapi - Okay for outsider, but not for Clan cats
Mistletoe - Compound names are sorta frowned upon {ex. Sandstorm}
Reindeer - The cats aren't aware what reindeer are, but they do know what deer/fawns are
Horse - The cats do know what horses are - especially in WindClan - so I suppose this is an acceptable name
Donkey - The cats aren't aware of what donkeys are