IPA: /ˌæntəˈnɪməs/
KK: /æn'tɑnəməs/
This word describes something that has a meaning that is opposite to another word.
The words 'hot' and 'cold' are antonymous.
Antonymous → It is formed from "anti-" (meaning against) and "onym" (from Greek "onuma", meaning name) and the suffix "-ous" (meaning full of). The word describes something that is full of names that are against each other, hence, words that have opposite meanings.
Think of 'anti-' meaning against and 'onym' meaning name — that's why antonymous refers to words that have names with opposite meanings.