LSJ
όν, or ὑπόστατος, ον, (< ὑφίσταμαι) set under; as Subst., ὑπόστατον, τό, stand, = ὑποστάτης, IG2². 1388.43, 11 (2).161 B 126 (Delos, iii BC), Paus. 10.26.9, Demiopr. ap. Poll. 10.46.
to be borne or withstood, οὐχ ὑποστατόν E. Supp. 737; θεὸς… θνητοῖς οὐδαμῶς ὑ. Id. Fr. 177.2 (as Scal. for -της).
substantially existing, Stoic. 2.114, A.D. Synt. 201.9, S.E. M. 10.60, Iamb. Comm. Math. 8.
Liddell-Scott-Jones, Greek-English Lexicon (9th ed., 1940)