The perceived length of time at which one actual minute passes in the visceral world of someone under the influence of THC. Most commonly, "weed time" constitutes a multiplicatively extended period from reality to visceral perception, e.g. 5 minutes seems more like 10-20 minutes (i.e. 5 real minutes equal 10-20 weed minutes).
"Hey, Benjarvis! How long till we reach our destination of 'Burger King?'"
"Well see, Ermelinda, it'll probably be about 10 more minutes. But since we are high on 'THC,' the perceived amount of time will most likely be far greater than that - say, half an hour in 'weed minutes,' as they are called."
"Oh, cinnamon and gravy!"