container bulgariaksi - Sanakirja.org (englanti-bulgaria)

An item in which objects, materials or data can be stored or transported.
A very large, typically metal, box used for transporting goods (also cargo container).
(by extension) someone who holds people in their seats or in a (reasonably) calm state.
(computing) A file format that can hold various types of data.
(computing, GUI) Any user interface component that can hold further (child) components.

As the MP4 container can store audio, video, or both, the M4A naming and file extension is used to hint that this MP4 container holds solely audio information.

Monikko