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.
v. lacked, lack·ing, lacks
To be without or in need of: lacked the strength to lift the box.
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.
[Middle English, perhaps from Middle Dutch lac, deficiency, fault.]
Usage Note: When lack is used in the sense "to be wanting or deficient," it is typically followed by in: You will not be lacking in support from me. When lack is used in the sense of "to be in need of something," it is often followed by for: "In the terrible, beautiful age of my prime, / I lacked for sweet linen but never for time" (E.B. White).
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.