instantĭa (noun F) : insto.
* Lit., a being near or close upon, hence presence: futura quorum consequenti tempore vera erit instantia, ea vera dicimus,Cic. Fat. 12, 27 B. and K.: infestus dicitur ab instantia atque imminentia fraudis, the immediate and threatening character of the injury, Nigid. ap. Gell. 9, 12, 6.
* Trop., steadiness, constancy, perseverance; force, vehemence in speaking; earnestness in supplication, importunity, urgency (post-Aug.): quid est enim, quod haec instantia non possit efficere?Plin. Ep. 3, 5, 18: oratio maxime vi, amaritudine, instantiā placet,id. ib. 5, 8, 10; opp. tarditas,Sol. 2, 46: repetendi debiti instantia,Dig. 32, 1, 32: sed instantia Byrrhaenae perfecit, ut vellet,App. M. 2, p. 123, 38: pertinaci negare instantia,Amm. 28, 1, 19.

s. TLL