pronounced: moon-kaf

1. A misshapen foetus; a monstrosity or freak.
2. a person with a mental handicap; a born fool.
3. a person who gazes at the moon or idles time away; an absent-minded person.
4. An animal imagined to inhabit the moon.

Briefly, "the realization that each random passerby is living a life as vivid and complex as your own." Originally from the Dictionary of Obscure Sorrows, which has a lot more beautiful neologism definitions like this you might enjoy.

A woman with massive cankles.

Plural: mooncalves