cook up . cook up {v.}, {informal} To plan and put together; make up; invent. The boys cooked up an excuse to explain their absence from school. Categories: add yours {informal} {v.} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2024 To section: C Subscribe to: American IdiomsIdioms feedEnglish languageHome page and general feed Add my comment