Lewis & Short

impărĭlĭtas (inp-), ātis, f. [imparilis],

  1. I. inequality, difference (very rare): imparilitas haec turbat observationem omnisque ratio disciplinae confunditur, lack of correspondence between the situations of the stars and the varied fates of men, Nigid. ap. Gell. 14, 1, 22.
  2. II. Gram. t. t.: soloecismus Latino vocabulo a Sinnio Capitone ejusdemque aetatis aliis imparilitas appellatus, Gell. 5, 20, 1.