This article is from the soc.culture.australian FAQ, by Stephen Wales with numerous contributions by others.
"Koala" is a bastardisation of a word from an Australian language. As
stated, the question doesn't really have an answer, as there were
around 200 Australian languages at the time of European contact, and
while many if not all of these are fairly closely related, there are
many different words for koala. "Koala" appears to be a misreading of
"kuu(l)la", the word for Koala in certain languages of the Sydney
region. [CM]
 
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