Pl. brothers-german (formerly brethren-). [f. BROTHER sb. + GERMAN.] A brother through both parents; a whole brother.
Early writers also used it as = brother on the mothers side, brother-uterine; it has been proposed in modern times to restrict it to brother on the fathers side.
1340. Ayenb., 146. Broþer germayn of uader and of moder.
c. 1450. Merlin, viii. 122. Thei be men of high lynage, and be bretheren germain.
1480. Caxton, Chron. Eng., ccxxv. 230. Karoll the grete kyng of fraunce was broder germayn of Quene Isabell kynge Edwardes moder.
1530. Palsgr., 201/2. Brother germayne, frere germain.
1751. Chambers, Cycl., s.v. German, Brother German denotes a brother both by the fathers and mothers side.
1882. A. Macfarlane, Consanguinity, 8. I use the term brother-german, to denote brother on the fathers side.