a brother whose parents are the same as one's own.
Middle English word dating back to 1350–1400
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
How to use whole brother in a sentence
“Now I love him as if he were my whole brother,” Hugh said warmly.The Secret Cache | E. C. [Ethel Claire] Brill