Drag Retrieve is typically a rod retrieve, but not always, where the rod moves vertically or horizontally at a speed that ensures the lure stays in contact with the bottom. Drag retrieve is similar to the reel retrieve called slow-roll retrieve which is generally a horizontal presentation bouncing off the bottom/cover.

Alias and Comparisons:

• Worm Retrieve: Some refer to a drag retrieve as a worm retrieve as it is a common retrieve for lures using worm soft plastics.
• Strolling: Leaving the lure on the bottom use the trolling motor to slowly drag the lure. Albeit not common, it is more common fishing deep. 
• Drag vs Slow Roll Retrieve: Slow roll is similar as the lure is moving slowly occasionally coming into contact with cover or bottom but a slow roll is a reel retrieve.