Dank means unpleasantly damp and cold. A dank cellar, dank air, dank and dark.
It is always negative and always about enclosed spaces — cellars, tunnels, caves — where damp and cold together make the air feel heavy. It is stronger and more unpleasant than damp. In internet slang, dank memes means excellent ones, which is an entirely separate and ironic use borrowed from cannabis slang. Note dankness.
1adjectivedankUnpleasantly damp and cold.
“The prisoners were kept in a dank cell with water running down the walls.”
dank is a quality of cold dampness.
Middle English danke is probably Scandinavian, related to Swedish dank, a marshy spot. The whole family is about wet ground.
Proto-Germanic
*dankwaz — dark
Middle English
danke — wet, damp; dampness, moisture
English, today
dank
From Middle English danke (“wet, damp; dampness, moisture”), probably from gmq, related to Swedish dank (“marshy spot”), Icelandic dökk (“pool”), Old Norse dǫkk (“pit, depression”), from Proto-Germanic dankwaz (“dark”). However, some trace it to a gmw source such as Dutch damp (“vapor”) or Middle High German damph, both ultimately from Proto-Germanic dampaz (“smoke, steam, vapor”). Modern slang senses derived from the drug sense; compare based (“awesome, especially in a right-wing context online”) from drug terminology freebased.
Etymology from Wiktionary, CC BY-SA