also: おにっこ
child born with teeth
Traditional term for a baby born with teeth already erupted, sometimes considered an ill omen in folklore.
child unlike its parents; changeling
Refers to a child who does not resemble its parents, sometimes with a supernatural connotation like a changeling. Rare in modern usage.
wild child; badly-behaved child
Used for a child who is unruly, mischievous, or difficult to control. Can be used figuratively.
That kid is known around the neighborhood as a little terror.
In old tales, a child born with teeth was feared as an onigo.
Onigo is an old word for a child who does not resemble its parents.
Standard kanji spelling for the reading おにご.
Kanji spelling also used for the reading おにっこ, though 鬼っ子 is more explicit.
Alternate spelling with small っ, more clearly indicating the reading おにっこ.
Compound of 鬼 (oni, 'demon, ogre') and 子 (ko, 'child'). The exact historical derivation is uncertain, but the word has been used since at least the Edo period to refer to unusual or difficult children.