filino

Filino is not its own word so much as a sum: the root fil- plus the feminine suffix -in-. The same machine gives you patro and patrino, frato and fratino, knabo and knabino, so learning one pair teaches you a hundred. The prefix ge- collects both sexes, so gefiloj means children of a family regardless of who is who, and filineto is a little daughter. Note that filino says nothing about age: a woman of sixty is still somebody's filino. For a child in general, unrelated to any parent, you want infano.