interjection Citizens Band Radio Slang.
(used to express affirmation or confirmation).
Compare ten code.
Origin of ten-four
First recorded in 1960–65
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for ten-four
Historical Examples of ten-four
Ten-four meant ten and a half; for in those primitive days knots were divided into eight fathoms.From Sail to Steam, Recollections of Naval Life
Captain A. T. Mahan