Definition of "Stemmer" :

noun: a device for removing stems from fruit (as from grapes or apples)

noun: a miner's tamping bar for ramming packing in over a blasting charge

noun: an algorithm for removing inflectional and derivational endings in order to reduce word forms to a common stem

noun: a worker who makes or applies stems for artificial flowers

noun: a worker who strips the stems from moistened tobacco leaves and binds the leaves together into books