lack

n.

1. The state of being lacking

   destitution, absence, need, dearth, shortage, paucity, deprivation, deficiency, deficit, scarcity, exiguity, exigency, insufficiency, inadequacy, privation, poverty, distress, scantiness.

   Antonyms plenty*, sufficiency*, abundance. *

2. That which is lacking

   need, decrease, want, loss, depletion, shrinkage, shortage, shortness, short fall, shortcoming, abridgment, defect, meagerness, scantiness, slightness, inferiority, paucity, stint, curtailment, retrenchment, reduction; see also necessity 2.

   Antonyms wealth*, overflow*, satisfaction.

lack

v.

lack implies an absence or insufficiency of something essential or desired she lacks experience; want (in this sense, chiefly British) and need stress the urgency of supplying what is lacking this matter needs, or wants, immediate attention; require emphasizes even more strongly imperative need, connoting that what is needed is indispensable his work requires great powers of concentration