Correct spelling for the English word "sibred" is [sˈɪbɹəd], [sˈɪbɹəd], [s_ˈɪ_b_ɹ_ə_d] (IPA phonetic alphabet).
Condition of being related, of being children of the same parents.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.