spit up spit up {v.} To vomit a little. The baby always spits up when he is burped. Put a bib on the baby. I don't want him to spit up on his clean clothes. Categories: add yours clothes {v.} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2024 To section: S Subscribe to: American IdiomsIdioms feedEnglish languageHome page and general feed Discuss