Is there a different word for aunt?
Other than 'antaidh'? Not really, unless you said piuthar m' athair or piuthar mo mhàthair (literally, "my father's sister" and "my mother's sister").
Why then - MAS E DO THOIL E - is "antaidh" not translated as AUNT ... "auntie" sounds like a "little" aunt (compared to a bigger / taller / larger) aunt ?!