Definition of all-dayer in English:

all-dayer

noun

  • Something that lasts an entire day or most of a day, especially a social event or party.

Origin

Late 19th century; earliest use found in Daily Inter Ocean (Chicago). From all-day + -er, chiefly after all-nighter.

Pronunciation

all-dayer

/ˌɔːlˈdeɪə/