Definition of sib noun from the Oxford Advanced Learner's Dictionary

 

sib

 noun
noun
BrE BrE//sɪb//
 
; NAmE NAmE//sɪb//
 
(biology)
 
jump to other results
a brother or sister Word Origin Old English ‘related by birth or descent’, of unknown origin. Modern senses date from the late 19th and early 20th cents.
See the Oxford Advanced American Dictionary entry: sib