Watching as a devotional exercise or religious observance; an act or instance of this. Now rare (archaic) except in watch-night (see compounds 2).

spec. Keeping vigil as an act of devotion.

Abstinence from sleep, watching, practised as a religious observance: often coupled with fasting. Also, an instance of this; a night spent in…

A devotional watching, esp. the watch kept on the eve of a festival or holy day; a nocturnal service or devotional exercise. Chiefly in plural.

The action of passing or spending the night (in early use esp. in prayer); †an all-night vigil (obsolete).

an all-night vigil, esp. one kept by relatives beside the body of a dead person (cf. to set up 37 at set, v.1 phrasal verbs 2).