What is the origin of vespertine?

Vespertine “of, relating to, or occurring in the evening” derives from Latin vesper “evening,” which comes from a Proto-Indo-European root with the same sense. Through this root, vesper is a cognate of the English term west, with a shift in definition because of the direction of the sunset. As we learned with the recent Word of the Day aureate, which may be related to east and Latin aurōra “dawn,” there is often an overlap between the cardinal directions and the location of the sun. Another distant relative of vesper is Ancient Greek hésperos “evening,” and its derivative Hesperus “evening star” is a nickname for the planet Venus. Vespertine was first recorded in English at the turn of the 16th century.