"place (papers) in consecutive order for future reference," mid-15c., from Old French filer "string documents on a thread or wire for preservation or reference" (15c.), earlier "to spin thread," from fil "thread, string" (12c.), from Latin filum "a thread, string; thread of fate; cord, filament," from PIE *gwhis-lom (cognates: Armenian jil "sinew, string, line," Lithuanian gysla "vein, sinew," Old Church Slavonic zila "vein"), from root *gwhi- "thread, tendon." The notion is of documents hung up on a line in consecutive order for ease of reference.Methods have become more sophisticated, but the word has stuck. Meaning "place among the records of a court or office" is from 1510s; of newspaper reporters sending in stories, 1954. Intransitive sense "march in a line (as soldiers do) one after another" is from 1610s. Related: Filed; filing.

"to smooth or abrade with a file," early 13c., from Old English filian, from the source of file, n.2. Related: Filed; filing.

1520s, "string or wire on which documents are strung," from French file "a row" (15c.), noun derived from Middle French filer "string documents; spin thread" (see file, v.1). The literal sense explains why from the beginning until recently things were generally on file (or upon file). The meaning "collection of papers systematically arranged for ready reference" is from 1620s; computer sense is from 1954. The sense "row of persons or things one behind another" (1590s) is originally military, from the French verb in the sense of "march in file." Meaning "line of squares on a chessboard running directly from player to player" is from 1610s.

metal tool for abrading or smoothing, Old English feol (Mercian fil) "file," from Proto-Germanic *fihalo "cutting tool" (cognates: Old Saxon fila, Old High German fila, Middle Dutch vile, Dutch vijl, German Feile), probably from PIE *peig- (1) "to cut, mark by incision" (cognates: Old Church Slavonic pila "file, saw," Lithuanian pela "file;" see paint, v.). Century Dictionary (1906) lists 60 named varieties of them.