’cause (kôz, k?z)conj. Informal Because.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.cause (k?z) n., v. caused, caus?ing. n. 1. a person that acts or a thing that occurs so as to produce a specific result: the cause of the accident. 2. the reason or motive for some action: a cause for rejoicing. 3. good or sufficient reason: to complain without cause. 4. a. a ground of legal action. b. a case for judicial decision. 5. a principle, ideal, goal, or movement to which a person or group is dedicated: the Socialist cause; the human rights cause. v.t. 6. to be the cause of; bring about. Idioms: make common cause, to unite in a joint effort. [1175?1225; Middle English (