A nephew is a son of one's sibling or half-sibling, and a niece is a daughter of one's sibling or half-sibling. Sons and daughters of siblings-in-law are also referred to as nephews and nieces respectively, even though there is no blood relation.
1.
occur in turn repeatedly.
"bouts of depression alternate with periods of elation"
synonyms: be interspersed, follow one another, be staggered, take turns, take it in turns, work/act in sequence, occur in turn, occur in rotation