Language Geek Note: Technically, a acronym has to be able to be pronounced as a word; so HTML and CSS are not acronyms, but RAM, SCSI, etc, are. (Try saying them out loud.) (pst, try pronouncing SCSI as 'skuzzy'). Technically an abbreviation of this sort that is not an acronym is called an initialism. (Some more discussion on the theme of acronyms vs. initialisms in computing.) Thanks to RaymondBurgess for the heads-up on this one. Of course, we're not language geeks, so we don't care.
You could also try running wtf(6), which is part of the bsdgames package, to expand some acronyms.
Acronyms, abbreviations and initialisms defined in the wiki: