plain . plain or smooth sailing {n. phr.} An uncomplicated, unhampered, or easy course. For a graduate of such a famous university as he was, that assignment was plain sailing. Categories: add yours {n. phr.} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2024 To section: P Subscribe to: American IdiomsIdioms feedEnglish languageHome page and general feed Discuss