From the base of basis; profound (as going down), literally or figuratively -- deep, very early.
see GREEK basis
STRONGS NT 901: βαθύςβαθύς, βαθεῖα, βαθύ (cf. βάθος), deep; properly: John 4:11. metaphorically: ὕπνος, a deep sleep, Acts 20:9 (Sir. 22:7; often also in Greek writings); ὄρθρος (see βαθέως), Luke 24:1 ((Aristophanes vesp. 215); Plato, Crito 43 a.; Polyaen. 4, 9, 1; ἔτι βαθέος ὄρθρου, Plato, Prot. 310 a. (cf. also Philo de mutat. nom. § 30; de vita Moys. i. § 32)); τά βαθέα τοῦ Σατανᾶ, Revelation 2:24 (G L T Tr WH; cf. βάθος).