• firl-boy,
• virl-boy,
• birl-boy,
• hirl-boy,
• yirl-boy,
• tirl-boy,
• gurl-boy,
• gjrl-boy,
• gkrl-boy,
• gorl-boy,
• g9rl-boy,
• g8rl-boy,
• giel-boy,
• gidl-boy,
• gifl-boy,
• gitl-boy,
• gi5l-boy,
• gi4l-boy,
• girk-boy,
• girp-boy

The adjective form of "girl-boy" is "girl-boyish".

The plural form of "girl-boy" is "girl-boys".

The singular form of the word "girl-boy" is "girl-boy". This is because "girl-boy" already describes a single person who possesses characteristics typically associated with both girls and boys.