the.com/trimmer

means A tool or device that trims, cutting or neatening edges — whether a string trimmer for grass, hedge trimmer, or hair clipper — or, by extension, a person who shifts opinions to suit the prevailing wind.

from From the verb "trim," which traces back to Old English "trymman" (also "trymian") meaning to make firm, strengthen, arrange, or set in order. The "-er" suffix simply names the doer or the doing-thing. The nautical world stretched it: to "trim" a ship was to balance its cargo and sails just so, which gave us the figurative "trimmer" — someone who balances between opposing sides to keep themselves comfortably afloat, neither too far port nor starboard.