Merged compressed-sensing onto compressive-sensing because there are many more compressive-sensing than compressed-sensing questions (88 vs 16) and all 16 compressed-sensing are double-tagged with compressive-sensing.
Also made compressed-sensing a synonym of compressive-sensing, it shouldn't reappear.
You're right, these are synonymous.
I've created a synonym suggestion, and users with a few answers on the tag can vote for it.
I believe since this is really just a matter of expanding an acronym, a moderator might be able to expedite the process.
Sure, we can do that! Which way do you suggest? fm as the tag and frequency-modulation as the synonym or the other way?
As suggested by @jojek, I've added fm as a synonym of frequency-modulation so frequency-modulation is the main one. See here.
OK, I've made the change you suggest.
Older Answer Below
I'd be tempted to go the other way: keep adc and dac and make the longer forms synonyms. Mainly because the shorter forms include "c" (for convertor), and adding that to the longer forms would make them a little long.