trim·mer 
(trĭmər)
(trĭmər)n.
1.
a. One that trims: a window trimmer.
b. A device or machine, such as a lumber trimmer, that is used for trimming.
2. One who changes one's opinions, especially in politics, to suit the needs of the moment.
3. Electronics A variable component used to make fine adjustments to capacity or resistance.
4. Architecture A beam across an opening, such as a hearth, into which the ends of joists can be fitted.