Lewis & Short

1. nĭger, gra, grum (gen. fem. nigraï, Lucr. 4, 537; comp. nigrior, Ov. H. 18, 7), adj., black, sable, dark, dusky (cf.: ater, pullus).

  1. I. Lit.: quae alba sint, quae nigra, dicere, Cic. Div. 2, 3, 9: quamvis ille niger, quamvis tu candidus esses, Verg. E. 2, 16: hederae nigrae, id. G. 2, 258: silvae (= umbrosae), Hor. C. 1, 21, 7: frons, id. ib. 4, 4, 58: collis, id. ib. 4, 12, 11: lucus, Ov. F. 3, 295 (for which atrum nemus, Verg. A. 1, 165): caelum pice nigrius, Ov. H. 18, 7: nigerrimus Auster, i. e. causing darkness, Verg. G. 3, 278; so, venti, Hor. C. 1, 5, 7: Eurus, id. Epod. 10, 5: nigros efferre maritos, i. e. killed by poison, Juv. 1, 71; cf.: pocula nigra, poisoned, Prop. 2, 20, 68 (3, 23, 10).
    Prov.: facere candida de nigris; nigra in candida vertere, to turn black into white, Juv. 3, 29; cf. Ov. M. 11, 315.
    Subst.: nĭgrum, i, n., a black spot, Ov. A. A. 1, 291.
  2. II. Trop.
    1. A. Of or pertaining to death: nigrorumque memor, dum licet, ignium (= lugubris rogi), of the funeral pile, Hor. C. 4, 12, 26: hora, Tib. 3, 5, 5: dies, the day of death, Prop. 2 (3), 19, 19: Juppiter niger, i. e. Pluto, Sen. Herc. Oet. 1705.
    2. B. Sad, mournful: domus, Stat. S. 5, 1, 18; Val. Fl. 3, 404.
    3. C. Unlucky, ill-omened: huncine solem Tam nigrum surrexe mihi? Hor. S. 1, 9, 72; Prop. 2, 21, 38 (3, 25, 4): lapis, the spot in the Comitium where Romulus or one of his adherents was slain, Paul. ex Fest. p. 177 Müll.
    4. D. Of character, black, bad, wicked: Phormio, nec minus niger, nec minus confidens, quam ille Terentianus est Phormio, Cic. Caecin. 10, 27: hic niger est, hunc tu, Romane, caveto, Hor. S. 1, 4, 85.

2. Nĭger, gri, m., a Roman surname: Aquilius Niger, Suet. Aug. 11.

3. Nĭger, gris, m., a river in Africa, Mart. Cap. 6, § 673; v. Nigris.

Nī̆gris, is (Nī̆gir, Vitr. 8, 2, 6; Nī̆-ger, Mart. Cap. 6, § 673), m., a river in the interior of Africa, now the Joliba or Niger, Plin. 5, 4, 4, § 30; 8, 21, 32, § 77.
Hence, Nī̆grītae, ārum, m., the people living near the Niger, Mel. 1, 4, 3; 3, 10, 4; Plin. 5, 8, 8, § 43.