ὑπό-στασις, -εως, ἡ
(ὑφίστημι, to set under, stand under, support) [in LXX for מַצָּב (1Ki.13:23 14:4 B), תִּקְוָה (Rut.1:12, Eze.19:5), etc., also in Wis.16:21 ;]
__1. a support, base or foundation (in various senses).
__2. substance (Arist., al.; opposite to φαντασία, ἔμφασις): Heb.1:3
__3. steadiness, firmness (Polyb., al.), hence, assurance, confidence: 2Co.9:4 11:17, Heb.3:14 11:1 (here perhaps title-deed, as that which gives reality or guarantee; see MM, xxv).†
(AS)