For example, AIM stands for AOL Instant Messenger, and AOL stands for American OnLine. This isn’t quite the same thing as a recursive acronym, which refers to itself. Maybe the term is nested acronym?
You're correct, it is in fact a nested acronym:
nested acronym: an acronym where one of the letters represents another acronym. e.g. AIM (AOL Instant Messenger)
You're also correct that it's not a recursive acronym, of which GNU (GNU's Not Unix) is the most infamous example:
recursive acronym: an acronym which refers to itself in the expression for which it stands. e.g. VISA standing for Visa International Service Association
It is also called a macronym or a multi-layered acronym, although the term "nested acronym" is more common:
A macronym, or nested acronym, is an acronym in which one or more letters stand for acronyms (or abbreviations) themselves. The word "macronym" is a portmanteau of "macro-" and "acronym".
Some examples of macronyms are:
- XHR stands for "XML HTTP Request", in which "XML" is "Extensible Markup Language", and HTTP stands for "HyperText Transfer Protocol"
- POWER stands for "Performance Optimization With Enhanced RISC", in which "RISC" stands for "Reduced Instruction Set Computing"
- VHDL stands for "VHSIC Hardware Description Language", in which "VHSIC" stands for "Very High Speed Integrated Circuit"
- XSD stands for "XML Schema Definition", in which "XML" stands for "Extensible Markup Language"
- AIM stands for "AOL Instant Messenger", in which "AOL" originally stood for "America Online"
- HASP stood for "Houston Automatic Spooling Priority", but "spooling" itself was an acronym: "simultaneous peripheral operations on-line"
- VORTAC stands for "VOR+TACAN", in which "VOR" is "VHF omnidirectional range" (where VHF = Very High Frequency radio) and "TAC" is short for TACAN, which stands for "Tactical Air Navigation"
Here's a deeply nested acronym (for fun): VITAL, which expands to "VHDL Initiative Towards ASIC Libraries", which further expands to "VHSIC Hardware Description Language Initiative Towards Application-Specific Integrated Circuit Libraries", which further expands to "Very High Speed Integrated Circuit Hardware Description Language Initiative Towards Application-Specific Integrated Circuit Libraries". That's 15 words long when fully expanded!