prepositionThe American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
On account of; by reason of.
Origin: Middle English bi cause of, by reason of : bi, by; see by1 + cause, reason; see cause + of, of; see of.