A person between aged 20-30 who is living in their parents house when they are old enough to live in his own apartment. I derived the term from the word "house-wife." A house-wife lives at home and spends her husband's money on silly things like clothes and jewelery. Likewise, a house-child (or house-daughter in this case) lives for free and spends her father's money on the same things.

A house-child, by definition, must be:
1) old enough to be a house-wife
2) unemployed
3) have lived away from the house for a period of time (i.e. college, grad school) and is now coming back to the house just when her parents thought they were finally rid of her!!
4) so busy house-childing that she frequently requests an assistant.
5) too old to live at home. Someone who is of normal age to live at home (i.e. a high-school student) cannot be a house-child.

Note: house-childing is becoming an increasingly popular activity given that most people in their 20s can no longer afford rent due to the current economic downturn