2. nīsus, ūs, m. [nitor], a pressing or resting upon or against, a pressure; a striving, exertion, labor, effort (mostly poet.; nixus in good prose, v. h. v.): pedetentim et sedato nisu, a tread, step, Pac. ap. Cic. Tusc. 2, 21, 48: pinnarum nisus inanis, a flight, Lucr. 6, 834; so, insolitos docuere nisus, Hor. C. 4, 4, 8: hic dea se primum rapido pulcherrima nisu Sistit, Verg. A. 11, 852: stat gravis Entellus nisuque immotus eodem, etc., in the same posture, id. ib. 5, 437: hunc stirps Oceani maturis nisibus Aethra Edidit, pains, throes, labor of parturition (v. 2. nixus), Ov. F. 5, 171.
In prose: tamquam nisus evomentis adjuvaret, retchings, Tac. A. 12, 67: uti prospectus nisusque per saxa facilius foret, Sall. J. 94, 1 Dietsch: quae dubia nisu videbantur, id. ib. 94, 2 Dietsch: non pervenit nisu sed impetu, Quint. 8, 4, 9; 1, 12, 10.