IPA: /ˈoʊvərˌsaɪzd/
KK: /ˈoʊvərˌsaɪzd/
Something that is larger than the usual size for that type of item.
She wore an oversized sweater that looked very cozy.
Comparative: more oversized
Superlative: most oversized
Oversized → It is formed from "over-" (meaning excessively or beyond) and "size" (from Old French *size*, meaning dimension or magnitude). The word "oversized" means excessively large or beyond the normal size.
Think of something that is 'beyond' ('over-') its normal 'dimension' ('size') — that's why oversized means too large.