noun
orphan; child left by the deceased
Refers to a child whose parent(s) have died. Often used in formal, literary, or news contexts. Not a casual everyday word; 孤児 (こじ) is more common for 'orphan' in general.
戦争で親を亡くした遺児たちを支援する団体がある。
There is an organization that supports children who lost their parents in the war.
彼は交通事故で両親を失った遺児だ。
noun
Rare, somewhat literary use for a child who has been abandoned or left behind. In modern Japanese, 捨て子 (すてご) is the usual word for an abandoned child.
昔話には、遺児が寺に拾われる話がよく出てくる。
In old tales, stories of abandoned children being taken in by temples often appear.
He is a child left parentless by a traffic accident.
Compound of 遺 (い, 'leave behind') and 児 (じ, 'child'). The kanji combination directly conveys the meaning of a child left behind, either by death or abandonment.