Ge-médren

According to the Old English Dictionary:

ge-médren

adj. Having the same mother, born of the same mother :-- Þá þrié gebróðor nǽron ná Philippuse gemédren (ge-médred, Bos. 60, 19), ac wǽron gefæderen fratres patri ex noverca genitos, Ors. 3, 7; 8. 114, 13. ge-medren