slack
5slack
nounDefinition of SLACK
: the finest screenings of coal produced at a mine unusable as fuel unless cleaned
Origin of SLACK
earlier sleck, probably from Middle Dutch slacke, slecke slag
First Known Use: 1729
Learn More About SLACK
Browse
Seen & Heard 
What made you want to look up slack? Please tell us where you read or heard it (including the quote, if possible).
