Definition - What does Roach mean?
In cannabis culture, a roach (slang) refers to the end of a smoked joint or blunt. In other words, roaches are what's left after a joint is smoked almost to completion. The remainder, the roach, is almost always too small to be smoked, due to the fear of burning ones fingers in the process.
Roaches are not to go to waste, however. Roaches can be smoked with a roach clip (made of a non-combustible material), or they can be saved with other roaches to be used to make a new, usually stronger, joint.
Groups of roaches can also be added to a bowl to smoke.
Hydrolife explains Roach
Due to it's higher amounts of resin, a roach is almost always brownish in color. This is due to the smoke deposits that settled each time the joint was inhaled. Also due to this higher resin content, a joint rolled from roaches gets a person higher than a regular joint would.
As the resin can damage the lungs, this method is to be done sparingly. One alternative is to add one or two roaches to fresh joints, which reduces the potency of making a joint entirely out of roaches.
In Europe, the United Kingdom, and most Commonwealth nations, the word roach more commonly refers to a short tube (filter) that some people add to the unlit end of a joint.
The word roach in this context can also refer to rolled tobacco cigarettes.