completely and without qualification; used informally as intensifiers
"an absolutely magnificent painting"
"a perfectly idiotic idea"
"you're perfectly right"
"utterly miserable"
"you can be dead sure of my innocence"
"was dead tired"
"dead right"
completely, entirely, to the fullest extent
"The storm left us utterly powerless to control our fate."
In plain English: Utterly means completely or totally without any doubt left over.
"I was utterly exhausted after working all night without sleep."
Usage: Use "utterly" primarily with negative adjectives or verbs to emphasize total negation, such as in "utterly useless," rather than pairing it with positive terms where "completely" might sound more natural. Avoid using it before nouns; instead, place it directly before the adjective or verb it modifies.
From utter + -ly.