One parent (one of the two parents).
彼の家族写真には片親しか写っていなかった。
Only one parent appeared in his family photo.
血縁関係を調べるため、片親の情報が必要だ。
To check biological relations, information about one parent is necessary.
出生届には父と母、どちらが片親になるかを記す欄があることもある。
Some birth registration forms have a field to indicate which person is the one parent.
A single parent (a parent raising a child alone).
片親で育った彼女は親子の関係がとても深い。
Raised by a single parent, she has a very close relationship with that parent.
片親家庭への支援制度が拡充された。
Support programs for single-parent households have been expanded.
彼は幼少期に片親に育てられたため、家事が得意だ。
Because he was raised by a single parent as a child, he's good at household tasks.