deficiencyn.[See Deficient.] The state of being deficient; inadequacy; want; failure; imperfection; shortcoming; defect.(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.()