Cases of microcephaly in babies have been linked to the Zika virus. [Wellcome Images CC BY-NC-ND 2.0]

microcephaly

/ ˌmaɪkroˈsɛfəli / noun

a medical condition in which the brain does not develop correctly and the head is smaller than normal:
Cases of microcephaly in babies have been linked to the Zika virus.

The adjective is microcephalic:
Microcephalic babies have a reduced life expectancy.

They try hard, but they’re still just Muggles! [photo by rmkoske CC BY-SA]

muggle

/ ˈmʌɡ^əl / noun

In the Harry Potter books, a Muggle is a person without magical powers:
Muggles feature prominently in Harry Potter fan fiction.

A muggle is a stupid person, or a person who does not have a particular type of knowledge or skill:
You stupid muggle! | I’m such a muggle when it comes to programming.