Someone who insists on nagging like a woman, and whining like a child simultaneously.
Alright Mom I'll walk the dog, you don't have to be such a Woman-Child about it.
An immature infant trapped inside the body of a grown woman.
This strange phenomenon generally occurs following the trauma of parentally-associated abandonment, neglect, or abuse during the fundamental "Attachment Period" of Infancy (0-3), and literally stops thier emotional development to the time of the first trauma sustained, and to no more than thier 3 year-old self. Officially, this is known as "Arrested Development". In modern psychology, a Woman-Child's childish alter-ego is also known as "the lost self", and is effectively, her true identity. "The false-self" on the other hand, is the well-perfected public persona, and false alter-ego she subconsciously developed as a way of coping with her initial infantile trauma - it's only those who develop close relationships with a Woman-Child, who manage to see just how immature and emotionally fragile she really is underneath this public persona. Arrested Development, and the Trauma (usually Abandonment) that caused this arrest, also culminate to create most of the emotional, psychological, and behavioural symptoms of a condition known as "Borderline Personality Disorder" (BPD).
Woman-Children are most easily recognised by thier fragile emotions, talking and behaving like little girls, falling in love with you far too quickly, missing you after very short periods of time (lack of "object constancy"), excessive crying, strong efforts to avoid abandonment in relationships, unpredictable actions, promiscuity, and the inability to have any form of serious or mature conversation when required.
"Her daddy left her as a baby - now she's stuck as a Woman-Child for life!"
"Dude, what's up with your girlfriend? She cries more than my little sister!"..."Don't worry about her dude - she's just a Woman-Child!"