A cherub was a supernatural being described in the Bible, explicitly as a guardian of the Garden of Eden. In some religions, a cherub was thought to be a type of youthful angel.
Doctor Julian Bashir referred to Lieutenant Hector Ilario as a "inspired cherub" during his toast to the skillful pilot in 2375. (DS9: "Field of Fire") Later that same year, Ezri Dax referred to Chief Miles O'Brien as "cherubic." (DS9: "The Changing Face of Evil")