Lewis & Short

Nĭŏba, ae, and Nĭŏbē, ēs, f., = Νιόβη.

  1. I. The daughter of Tantalus, and wife of Amphion, king of Thebes, whose seven sons and seven daughters were slain by Apollo and Diana, because, on the strength of her numerous progeny, she triumphed over Latona. Niobe herself was changed into a stone, which was transported in a whirlwind to the top of Sipylus, and has ever since remained wet with tears; form Niobe, Ov. M. 6, 146 sq.; form Nioba: Nioba fingitur lapidea, propter aeternum credo in luctu silentium, Cic. Tusc. 3, 26, 63; Sen. Ep. 63, 2; Prop. 2, 20 (3, 13), 7; Petr. 52, 2; Hyg. Fab. 9 and 145.
    Hence,
      1. 1. Nĭŏbēus, a, um, adj., of or belonging to Niobe: proles, Hor. C. 4, 6, 1.
      2. 2. Nĭŏbĭdes, ae, m., a son of Niobe, Hyg. Fab. 11 in lemm.
  2. II. The daughter of Phoroneus, king of Argos, who bore Argus to Jupiter, Hyg. Fab. 145.