Deficiency /(?)/

De·fi·cien·cy

Deficiency

n.

pl. Deficiencies

  1. The state of being deficient; inadequacy; want; failure; imperfection; shortcoming; defect.
    [Marlborough] was so miserably ignorant, that his deficiencies made him the ridicule of his contemporaries.
    — Buckle.

Phrases & Compounds
Deficiency of a curve
the amount by which the number of double points on a curve is short of the maximum for curves of the same degree.