Noun - In the context of Philadelphia/Delco this colloquialism is used to designate the time of day b/w 4-6am (depending on time of year) before the sun comes out fully. The time, sight and experience is known as the Gloom. Generally witnessed due to late night drinking
Verb - to be awake at this time of day usually in a drinking context. To gloom or gloom it is synonymous with binge drinking until ungodly hours
Aww man you look like shit. Out gloomin' it last night?
Yeah man whacked like 20 brews and motor-boated some hen