We found 2 dictionaries that define the word filename extensions:

General (2 matching dictionaries)

1. filename extensions: Wiktionary
2. filename extensions: Stammtisch Beau Fleuve Acronyms

(Note: See filename_extension as well.)

Definitions from Wiktionary (filename extension) ▸ noun:  (computing) Synonym of file extension. ▸ Also see filename_extension ▸ Words similar to filename extensions ▸ Usage examples for filename extensions ▸ Idioms related to filename extensions ▸ Wikipedia articles (New!) ▸ Words that often appear near filename extensions ▸ Rhymes of filename extensions ▸ Invented words related to filename extensions