1 文書を見つけるための辞書。

• filename extension, file name extension, extension
• 拡張子
• a string of characters beginning with a period and followed by one or more letters; the optional second part of a PC computer filename; "most applications provide extensions for the files they create"; "most BASIC files use the filename extension .BAS"
• ピリオドから始まり、一つ以上の文字が続く文字列