IPA: /ˌoʊvərˈsɪrɪəs/
KK: /oʊvərˈsɪrɪəs/
Being too serious, often to the point of being unable to relax or enjoy things.
His overserious attitude made it hard for others to have fun at the party.
Comparative: more overserious
Superlative: most overserious
Overserious → It is formed from "over-" (meaning excessively) and "serious" (from Latin "serius", meaning grave or important). The word "overserious" means excessively grave or important, indicating a lack of lightness or humor.
Think of being 'excessively' ('over-') 'grave' or 'important' ('serious') — that's why overserious describes someone who takes things too seriously.
No commonly confused words.