From a compound of hupo and histemi; a setting under (support), i.e. (figuratively) concretely, essence, or abstractly, assurance (objectively or subjectively) -- confidence, confident, person, substance.
see GREEK hupo
see GREEK histemi
1. a setting or placing under; thing put under, substructure, foundation: Psalm 68:3 2. that which has foundation, is firm; hence, a. that which has actual existence; a substance, real being: τῶν ἐν ἀερι φαντασμάτων τά μέν ἐστι κατ' ἐμφασιν, τά δέ καθ' ὑπόστασιν, Aristotle, de mundo, 4, 19, p. 395{a}, 30; φαντασίαν μέν ἔχειν πλούτου, ὑπόστασιν δέ μή, Artemidorus Daldianus, oneir. 3, 14; (ἡ αὐγή) ὑπόστασιν ἰδίαν οὐκ ἔχει, γεννᾶται δέ ἐκ φλογός, Philo de incorruptibil. mundi § 18; similarly in other writings (cf. Sophocles Lexicon, under the word, 5; Liddell and Scott, under the word, III. 2). b. the substantial quality, nature, of any person or thing: τοῦ Θεοῦ (R. V. substance), Hebrews 1:3 (Wis. 16:21; ἴδε ... τίνος ὑποστάσεως ἤ τίνος εἴδους τυγχάνουσιν οὕς ἐρεῖτε καί νομιζετε Θεούς, Epist. ad' Diogn. 2, 1 [ET]; (cf. Suicer, Thesaurus, under the word)). c. steadiness of mind, firmness, courage resolution (οἱ δέ Ῥόδιοι θεωροῦντες τήν τόν Βυζαντινων ὑπόστασιν, Polybius 4, 50, 10; οὐχ οὕτω τήν δύναμιν, ὡς τήν ὑπόστασιν αὐτοῦ καί τολμᾶν καταπεπληγμενων τῶν ἐναντίων, id. 6, 55, 2; add, Diodorus 16, 32f; Josephus, Antiquities 18, 1, 6); confidence, firm trust, assurance: 2 Corinthians 9:4; 2 Corinthians 11:17; Hebrews 3:14; Hebrews 11:1 (for תִּקְוָה, Ruth 1:12; Ezekiel 19:5; for תּוחֶלֶת, Psalm 38:8