When you talk suppressor to any of the folks that are important (i.e. can throw you in jail) most have no idea what you are talking about.
When I was trying to decide between individual and trust, I was talking to the folks at the local PD to make sure they would sign off if I went individual, and after about the second time mentioning "suppressor", they asked me what the heck I was talking about? When I said silencer, everybody knew, so that's the term I now use.
Nowhere on any of the ATF forms I've filled out does it mention suppressor-it's always silencer or muffler.
If you download the 243 page Federal Firearms Regulations Reference Guide, you can do a search for suppressor and will find it mentioned a grand total of two times as it pertains to sound devices (plenty of references to flash suppressors).
From the 207 page ATF National Firearms Act book, you will find suppressors (as it relates to sound devices) mentioned once.
I got tired of counting the number of times muffler was mentioned.
As such, I now just call 'em silencers so anybody that matters is on the same page.
Hey, if you really want to watch the heads of the PC crowd explode, start calling 'em mufflers!