WordWeb Online

1. Of or characteristic of or occurring in spring
   "the vernal equinox"
    
2. Suggestive of youth; vigorous and fresh
   "he is vernal for his age";
   - youthful, young

See also: early-blooming, early-flowering, immature, late-spring-blooming, spring-blooming, spring-flowering, young

Antonym: autumnal, summery, wintry

Encyclopedia: Vernal, UT µSA