1. A complete absence of a particular thing: Lack of sleep made it difficult for Bianca to concentrate on her studies.

Royce's lack of a university education disturbed him as he grew older.

2. Something which is needed but is in short supply or is not available: Lacks of sufficient food for Emilio resulted in his having a weakened condition.
3. A particular deficiency or absence of something: Blaine had a lack of funds that were necessary to start his business.

The police charges against Karl were dropped for lack of evidence.

4. A situation in which there is not enough of something: The flowers died because there was a lack of moisture and so the soil was too dry.

1. To not have enough of something that is desired: The author's book lacks proper structure or interest.

The mother lacks the money that is needed to buy new shoes for her children.

2. To have too little of something: What Michael lacks in patience, he makes up for it in determination.
3. To fall short by a small amount: Barbara was lacking just ten cents of having the full amount to pay for the magazine that she wanted to buy.