Fervent

Having or displaying a passionate intensity.

From Middle English fervent, from Old French fervent (modern French fervent), from Latin ferventem, the accusative masculine or feminine singular form of fervēns (“burning, fiery; hot; zealous; etc.”), the present active participle of ferveō (“to burn; to be hot; (figurative) to be agitated, fired up, or inflamed; etc.”), ultimately from Proto-Indo-European *bʰrewh₁- (“to boil; to brew”).

fervid