English noun: filename extension
|1.||filename extension (communication) a string of characters beginning with a period and followed by one or more letters; the optional second part of a PC computer filename|
|Samples||Most applications provide extensions for the files they create.|
Most BASIC files use the filename extension .BAS.
|Synonyms||extension, file name extension|
|Part meronym||computer file name, computer filename, file name, filename|