errant UK /ˈɛɹ(ə)nt/US /ˈɛɹənt/adjective 3noun 1forms 3 adjective3 •Straying from the proper course or standard, or outside established limits.In that there are just seven Planets or errant Stars in the lower Orbs of heaven: but it is now demonstrable unto sense, that there are many more — 1650 •Prone to erring or making errors; misbehaving.We ran down the street in pursuit of the errant dog. •Roving around; wandering. noun1 •A knight-errant. formserrants · more errant · most errant