If you want to use "utter" as a noun it would be "utterance" and it has its own meaning: http://www.dictionary.com/browse/utterance As you can see, it is related to voice/speaking, etc., as one of possible sense of the verb "utter" is just that (speak, pronounce, etc.). At least in my area (Linguistics), "utter" and "utterance" are commons words and they always mean something related to voice.

Sháun has a good explanation of the adjectival form of "utter," which is the form used in the example you give about machines. It can also be used as a verb: "to utter" = to make a sound with one's voice Example: "He was unable to utter even the smallest complaint, despite how badly his boss was treating him." It often has a negative connotation ("to utter threats against another person") or a "pathetic" connotation, as in the example above, where we might see the man as "weak" or "pathetic" for not being able to complain about his boss.

The word utter can be used to describe the purest, the complete, the ultimate etc. For example, 'the uttermost' would be the highest form. "He was a complete stranger." To emphasise this sentence you may use 'utter' and change this to; "He was a complete and utter stranger." Meaning the ultimate stranger.

Lynne, thank you so much for your answer and examples. They're really clear and helpful. Thanks again. Matías. PS: I'm glad that you've found my message.

I think of utter as absolute - He's an utter failure. It's never a noun, always an adj. or a verb when used to mean speak or make a sound - he uttered a sound like an animal - he uttered his last words in a whisper I can't find the answer that you apparently sent to me., Lynne