HALF-SIB Meaning of HALF-SIB in English ˈ ̷ ̷| ̷ ̷ nounalso half-sibling ˈ ̷ ̷| ̷ ̷ ̷ ̷ : a half brother or half sister — compare sib Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012