rătĭōcĭnor, ātus, 1
* V. dep. n. and a. [ratio] (rare, but good prose).
* Lit., to reckon, compute, calculate: in summo apud illos (sc. Graecos) honore geometria fuit: itaque nihil mathematicis illustrius; at nos metiendi ratiocinandique utilitate hujus artis terminavimus modum,Cic. Tusc. 1, 2, 5: de pecuniā ratiocinari,id. Inv. 2, 39, 115; 2, 32, 125; Vitr. 10, 15.
* Transf.
* To consider, deliberate, meditate: quo pacto cum illis occipiam, id ratiocinor,Plaut. Stich. 1, 2, 18: socii profecto ratiocinati essent quid possent facere, si quidem suā sponte facerent,Auct. Her. 4, 11, 16.
* To reason, argue, to infer or conclude from a consideration of circumstances: id ex partibus juris sumi oportebit et ratiocinari, quid in similibus rebus fieri soleat, et videre, utrum, etc.,Cic. Inv. 2, 20, 61; cf. Auct. Her. 2, 23, 35; Quint. 7, 1, 61: etenim sic ratiocinabantur ... aperte jam ac perspicue nulla esse judicia, etc.,Cic. Verr. 1, 7, 20; cf. id. Mil. 12, 32; id. Phil. 2, 22, 55.—Rarely with acc.: mores atque parsimoniam alicujus,App. M. 1, p. 113, 5.

s. TLL