Md. Code, Family Law § 9.5–301

(a) In this subtitle the following words have the meanings indicated.

(b) “Petitioner” means a person who seeks enforcement of an order for return of a child under the Hague Convention on the Civil Aspects of International Child Abduction or enforcement of a child custody determination.

(c) “Respondent” means a person against whom a proceeding has been commenced for enforcement of an order for return of a child under the Hague Convention on the Civil Aspects of International Child Abduction or enforcement of a child custody determination.