1. One that actively contributes to an accomplishment, result, or process: "Surprise is the greatest factor in war" (Tom Clancy). See Synonyms at element.
a. One who acts for someone else; an agent.
b. One who purchases accounts receivable at a discount.
3. Mathematics One of two or more quantities that divides a given quantity without a remainder. For example, 2 and 3 are factors of 6; a and b are factors of ab.
4. A quantity by which a stated quantity is multiplied or divided, so as to indicate an increase or decrease in a measurement: The rate increased by a factor of ten.
5. A gene. No longer in technical usage.
6. Physiology A substance that functions in a specific biochemical reaction or bodily process, such as blood coagulation.
v. fac·tored, fac·tor·ing, fac·tors
To determine or indicate explicitly the factors of: If you factor 70, you get 2, 5, and 7.
To engage in purchasing accounts receivable at a discount.
To figure in: factored vacations in when preparing the schedule.
[Middle English factour, perpetrator, agent, from Old French facteur, from Latin factor, maker, from facere, to make; see dhē- in the Appendix of Indo-European roots.]
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.