'Nipper' defines a wide variation of inferior or otherwise shitty marijuana. Nipper has a substancially lower percentage of THC compared to quality product and often comes damp and darker looking. Nipper produces a much less enjoyable experience and overall a low quality high.
Nipper can be easily detected by its smell and taste. Nipper often has the smell of hay or wet grass and the quality of smoking toxic fumes. There are different variations of nipper bud, some having less THC, however some nipper bud can be tolerated.
Generally you could define nipper bud as shitty weed. Maybe the weed was picked too early and/or not let dry long enough, or maybe the grower just didn't have a flying fuck what he was doing.
"yo this sucks, all i could get was this shitty nipper."
"i hate nipper bud, i wish i had some white widow"