Lewis & Short

ĭners, ertis (abl. inerti, Plin. 16, 43, 83, § 227:

  1. I. inerte, Ov. P. 1, 5, 8; 1, 10, 14), adj. [2. in-ars], unskilled in any art or trade, without skill, unskilful (class.): ut perhibetur iners, ars in quo non erit ulla, Lucil. ap. Serv. ad Verg. A. 4, 158: artes, quibus qui carebant, inertes a majoribus nominabantur, Cic. Fin. 2, 34, 115: versus, artless ( = sine arte et gravitate facti), Hor. A. P. 445.
    In partic., = iners dicendi, arte dicendi carens: homo non inertissimus, Cic. Div. in Caecil. 21, 67.
  2. II. In gen., inactive, idle, indolent, sluggish, inert.
    1. A. Of living beings: linguā factiosi, inertes operā, Plaut. Bacch. 3, 6, 13: silvicolae homines bellique inertes, Naev. ap. Macr. S. 6, 5, § 9: gerro, iners, etc., Ter. Heaut. 5, 4, 10: vicissent inprobos boni fortes inertes, Cic. Sest. 19, 43: senectus, id. de Sen. 11, 36: homo inertior, ignavior proferri non potest, id. Verr. 2, 2, 78, § 192: pecus, Verg. A. 4, 158; cf.: fera membris, Plin. 8, 21, 32, § 77.
    2. B. Of inanim. and abstr. things: inertissimum et desidiosissimum otium, Cic. Agr. 2, 33: inertissima segnitia, id. Fin. 1, 2, 5: ignavum et iners genus interrogationis, empty, idle, id. Fat. 13, 29: aquae, stagnant waters, Ov. H. 18, 121: stomachus, i. e. without digestion, id. P. 1, 10, 14: glaebae, that bear nothing, without cultivation, Verg. G. 1, 94: terra, motionless, immovable, Hor. C. 3, 4, 45: horae, leisure hours, id. S. 2, 6, 61: tempus, Ov. P. 1, 15, 44: Brutus castigator lacrimarum atque inertium querellarum, Liv. 1, 59, 4.
      Of food, without flavor, insipid: caro, Hor. S. 2, 4, 41: blitum iners videtur, ac sine sapore, aut acrimonia ulla, Plin. 20, 22, 93, § 252: sal, id. 31, 7, 39, § 82: vita, inactive, quiet, Tib. 1, 1, 5.
      Poet., causative, rendering idle or inactive: frigus, Ov. M. 8, 790: somni, id. Am. 2, 10, 19.
      Hence, adv.: ĭnerter, and sup. inertissime, Charis. 165 P.