"To be exact......TBD is an acrynonym"

To be pedantic, it is just an abbreviation - not an acronym.

A true acronym is a special case of an abbreviation, where the abbreviation is itself a word (or name); eg
BASIC = Beginner's All-purpose Symbolic Instruction [1] Code


[1] BASIC was invented as a school teaching language, so I'm not sure whether the 'I' originally stood for "Instruction" or "Instructional"