fillet (n.) Look up fillet at Dictionary.com
early 14c., "headband," from Old French filet (12c.) "thread, filament; strip, ligament," diminutive of fil "thread" (see file (v.)). Sense of "cut of meat or fish" is from late 14c., apparently so called because it was prepared by being tied up with a string. As a verb, from c.1600, "to bind with a narrow band;" meaning "to cut in fillets" is from 1846. Related: Filleted; filleting.