Definitions 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
• name:  A surname (very rare: popularity rank in the U.S.: #54039)