circumstantĭa (noun F) : circumsto (post-Aug. and rare).
* A standing round, a surrounding: hostium,Gell. 3, 7, 5: aquae, aëris,Sen. Q. N. 2, 7, 2 (as transl. of the Gr. ἀντιπερίστασις).—*
* Concr., a surrounding circle, a band, troop: angelorum,Tert. Or. 3.
* Trop., the state, condition, circumstances, attribute, quality: rerum negotiorumque,Gell. 14, 1, 15; 14, 2, 2; Tert. Bapt. 17: hoc genus argumentorum sane dicamus ex circumstantiā, quia περίστασιν dicere aliter non possumus, * Quint. 5, 10, 104.

s. TLL