Why is the ninth month called September?
"to place (papers) in consecutive order for future reference," mid-15c., from Middle French filer "string documents on a wire for preservation or reference," from fil "thread, string" (12c.), from Latin filum "a thread, string," from PIE *gwhis-lom (cf. 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.
File (filacium) is a threed or wyer, whereon writs, or other exhibits in courts, are fastened for the better keeping of them. [Cowel, "The Interpreter," 1607]Methods have become more sophisticated, but the word has stuck. Related: Filed; filing.
1520s, "string or wire on which documents are strung," from French file "row," from Middle French filer (see file (v.)). The meaning "arranged collection of papers" is from 1620s; computer sense is from 1954. The military sense "line or row of men" (1590s) is from the French verb in the sense of "spin out (thread); march in file."
metal tool, Old English feol (Mercian fil), from Proto-Germanic *finkhlo (cf. Old Saxon and Old High German fila, Middle Dutch vile, Dutch vijl, German Feile), probably from PIE *peig- "to cut, mark by incision" (see paint (v.)). The verb in this sense is from early 13c., from Old English filian. Related: Filed; filing.
[first sense perhaps fr the tool; perhaps related to French filou, ''pickpocket'']