Lewis & Short

testu or testum, i, n. [testa], a vessel or lid which was placed over food, etc., to be cooked, and then covered with hot coals, usually of earthenware.

  1. I. Lit.: in foco caldo sub testu coquito leniter, Cato, R. R. 75: sub testu, id. ib. 74; cf.: et fumant testu pressus uterque suo, Ov. F. 5, 510: fimo ovium sub testo calefacto, Plin. 30, 13, 39, § 114: unguito focum, ubi coquas, colfacito bene et testum, Cato, R. R. 76, 2.
    Abl. testo, Cato, R. R. 76, 4; 84, 2; Verg. M. 51.
    Afterwards of metal: ranarum corda sub aereo testo discoxere, Plin. 32, 7, 26, § 81.
  2. II. Transf., an earthen vessel, earthen pot: ara fit: huc ignem curto fert rustica testu, Ov. F. 2, 645; Petr. 136; Mumm. and Afran. ap. Charis. p. 118 P.