(countable) The period between sunset and sunrise, when a location faces far away from the sun, thus when the sky is dark.

A town in East Northamptonshire district, Northamptonshire, England (OS grid ref SP9566). / A village in North Hertfordshire district, Hertfordshire, England (OS grid ref TL3031).

plural of overdistension

(Internet slang, text messaging) Initialism of how the fuck.