Vesper n. : The evening star; Hesper; Venus, when seen after sunset; hence, the evening.

Vesper a. : Of or pertaining to the evening, or to the service of vespers; as, a vesper hymn; vesper bells.

Example:
How Vesper theory is useful in explaining the shapes of molecules?

Taxonomy
Vesper, cocktail, Kina Lillet, Lillet Blanc, goblet, proof, measure, gin, champagne, lemon peel, James Bond, Bond, free encyclopedia, ingredients, Vesper Martini, substitutes, Esquire, garnish.

Defination from the web:
Vesper or Vesper Martini is a cocktail that was originally made of gin, vodka, and Kina Lillet (the closest modern equivalent is Lillet Blanc) ... A "Green Vesper" substitutes absinthe for the Kina Lillet. Lime peel may be substituted for lemon. ...