1. Deficiency or absence: Lack of funding brought the project to a halt.
2. A particular deficiency or absence: Owing to a lack of supporters, the reforms did not succeed.

1. To be missing or deficient: We suspected that he was lying, but proof was lacking.
2. To be in need of something: She does not lack for friends.

Synonyms: These verbs mean to be without something, especially something that is necessary or desirable. Lack emphasizes the absence of something: She lacks the money to buy new shoes. The plant died because it lacked moisture.
Want and need stress the urgent necessity for filling a void or remedying an inadequacy: "Her pens were uniformly bad and wanted fixing" (Bret Harte). The garden needs care.

Usage Note: When lack is used intransitively, the present participle is generally followed by in: You will not be lacking in support from me. Other forms of the intransitive verb are most often followed by for: In the terrible, beautiful age of my prime,/I lacked for sweet linen but never for time (E.B. White).