Lewis & Short

mĕdĭō̆crĭtas, ātis, f. [mediocris].

  1. I. A middle state, a medium, mean; moderateness, moderation (class.): mediocritatem illam tenere, quae est inter nimium et parum, Cic. Off. 1, 25, 89; 1, 39, 140: in dicendo, mediocrity, id. de Or. 1, 25, 117: dicendi, id. Brut. 66, 235: vultus, i. e. a medium between excessive gayety and over-seriousness, Auct. Her. 3, 15, 26: auream quisquis mediocritatem Diligit, Hor. C. 2, 10, 5.
    Of style: cum omnis virtus sit mediocritas, Cic. Brut. 40, 149: mediocritatis (exemplum esse) Terentium, Varr. ap. Gell. 6, 14, 6.
    In plur.: mediocritates illi probabant, moderate passions, Cic. Ac. 2, 44, 135: mediocritates vel perturbationum vel morborum animi, id. Tusc. 3, 10, 22.
  2. II. Meanness, insignificance, littleness, inferiority (rare but class.): hominum, Vell. 2, 130, 3: quod meae mediocritati conveniret, my insignificance, Gell. 14, 2, 25; cf.: mediocritas nostra, my modest self, Vell. 2, 111, 3: ingenii, Cic. Phil. 2, 1, 2: memoriae, Quint. 11, 2, 39.