IPA: /ˈblaɪθɪst/
KK: /blaiθɪst/
The happiest or most carefree; showing a cheerful and lighthearted attitude.
She was the blithest person at the party, spreading joy and laughter wherever she went.
Comparative: blither
Superlative: blithest
Blithest is formed from "blithe" (from Old English "blīðe", meaning happy or cheerful) and the suffix "-est" (indicating the superlative degree). The word "blithest" means the most happy or cheerful.
Think of the Old English word for happy, 'blithe', and remember that 'blithest' means the most cheerful.
No commonly confused words.