IPA: /ʌnˈfɪl.i.əl/
KK: /ʌnˈfɪlɪəl/
Not behaving in a way that is expected or proper for a child towards their parents.
His unfilial behavior shocked his family during the reunion.
Unfilial → It is formed from "un-" (meaning not) and "filial" (from Latin "filiālis", meaning of a son or daughter). The word "unfilial" means not behaving in a manner befitting a son or daughter, indicating a lack of respect or duty towards one's parents.
Think of 'not' ('un-') behaving like a 'son or daughter' ('filial') — that's why unfilial describes someone who does not act as a good child should.