a. 1. Knowing; wise; shrewd. [ Old Slang ] [ 1913 Webster ]

I said you were a gnostic fellow. Sir W. Scott. [ 1913 Webster ]

2. (Eccl. Hist.) Of or pertaining to Gnosticism or its adherents; as, the Gnostic heresy. [ 1913 Webster ]

n. [ L. gnosticus, Gr. &unr_; good at knowing, sagacious; as a n., man that claims to have a deeper wisdom, fr. gignw`skein to know: cf. F. gnostique. See Know. ] (Eccl. Hist.) One of the so-called philosophers in the first ages of Christianity, who claimed a true philosophical interpretation of the Christian religion. Their system combined Oriental theology and Greek philosophy with the doctrines of Christianity. They held that all natures, intelligible, intellectual, and material, are derived from the Deity by successive emanations, which they called Eons. [ 1913 Webster ]

n. The system of philosophy taught by the Gnostics. [ 1913 Webster ]