The English language is an amazing inheritance: every word a story.
In Norse thought we find the fascinating idea that, as with humanity, there are different tribes of gods. One of these tribes is known collectively as the Aesir. This is a plural form; the singular, unfortunately, is áss. In Icelandic, this rhymes with house, but there's no denying that it's jarring to the eye of the English-reader.*
The English-speaking ancestors knew these gods as well, but unlike the good old pagan word god, ôs came to refer specifically to a pagan god, and so fell out of common usage. Eventually the word became extinct.