A growl? An oath (by Jove!)? A snarl?
If you have nothing to snarl, swear, or growl at, then any public announcement is technically an utterance: so that must include anything on Facebook,or Twitter.
Or, I suppose, on a blog post.
For lawyers (English criminal lawyers, anyway (who aren't necessarily criminal: it's just that they deal with criminal law)) uttering involves the distribution of fake coins or banknotes. The utter in utter barrister, though, means a junior lawyer.
If you're utterly miserable that's another sort of utter entirely.
Unless you're a lawyer who's really really desperate to get promotion.
Thing To Do Today: utter. The speaking word comes from the Middle Dutch ūteren, to make known, and is related to the Middle Low German ūtern to sell or show. Utter meaning total comes from the Old English utera, which means outer.