Maximum usable frequency. In radio transmission using reflection from the regular ionized layers of the ionosphere, the upper frequency limit that can be used for transmission between two points at a specified time.

See Maximum Usable Frequency.

"Maximum Useable Frequency"; that frequency above which expected propagation no longer exists.

MUF (short for "Multi-User Forth") is a Forth-based programming language used on Tiny MUCK MUCK servers and their descendants, including Fuzzball MUCK, Proto MUCK and Glow MUCK.

Tool for knowledge acquisition / ontology building from narrative texts.

Material Unaccounted For. A term used in nuclear materials accountancy.