Lewis & Short

dīmĭdĭo, no perf., ātum, 1, v. a. [dimidius], to divide into two equal parts, to halve (as a finite verb, very rare): quid dimidias Christum? Tert. de Carn. Chr. 5.
Trop.: viri dolosi non dimidiabunt dies suos, i. e. shall not live half the life of men, Vulg. Psa. 54, 23; cf. also, id. Job, 21, 21; but freq. and class. in the perf. part. dīmĭ-dĭātus, halved, half (acc. to Varr. ap. Gell. 3, 14, 19, applied to a whole, which is divided into halves; whereas dimidius is applied to a half; or, as Gellius rightly explains it, dimidiatum nisi ipsum, quod divisum est, dici haud convenit; dimidium vero est, non quod ipsum dimidiatum est, sed quae ex dimidiato pars altera est; cf. however, dimidius, I.): homines dimidiati, Cato ap. Gell. l. l.; cf. id. R. R. 151, 3; and comic.: procellunt sese in mensam dimidiati (with half the body), dum appetunt, Plaut. Mil. 3, 1, 165; cf. also, transf.: dies quidem jam ad umbilicum est dimidiatus mortuus, id. Men. 1, 2, 45: luna, Cato ap. Plin. 16, 39, 75, § 194; cf. mensis, Cic. Verr. 2, 2, 52; id. Tusc. 2, 16: vas vini, Enn. ap. Gell. l. l.: porcus, Lucil. ib.; cf. Suet. Tib. 34: solea, Lucil. ap. Gell. l. l.: librum, fabulam legi, Varr. ib.; cf.: exesis posterioribus partibus versiculorum, dimidiatis fere, Cic. Tusc. 5, 23, 66; so the comic verse respecting Terence: tu quoque, tu in summis, o dimidiate Menander, etc., Caes. ap. Suet. Vita Ter. fin.