imaginitis

Noun

humorous uncountable

(humorous) A notional disease characterised by a hyperactive imagination.

Japanese Meaning

空想が異常に活発、あるいはその状態を皮肉的に「病」と表現するもの

わずかな雷鳴でも、マークは想像力過剰症のせいで、裏庭に海賊の一団が潜んでいると信じ込んでしまった。

Sense（1）

(humorous) A notional disease characterised by a hyperactive imagination.

Other dislodged stones, however, convinced us the boys had not suffered from imaginitis[…]