What does "deficiency" mean?

Deficiency: The state of being deficient; inadequacy; want; failure; imperfection; shortcoming; defect. "A deficiencyof blood." Arbuthnot. [Marlborough] was so miserably ignorant, that his deficiencies made him the ridicule of his contemporaries. Buckle. Deficiency of a curve (Geom.), the amount by which the number of double points on a curve is short of the maximum for curves of the same degree.