/ ˈʌtməʊst; NAmE -moʊst/ adjective , noun
■ adjective
(also less frequent ut·ter·most ) [ only before noun ] greatest; most extreme :
This is a matter of the utmost importance.
You should study this document with the utmost care.
■ noun
[ sing. ] the greatest amount possible :
Our resources are strained to the utmost.
He did his utmost (= tried as hard as possible) to persuade me not to go.
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WORD ORIGIN
Old English ūt(e)mest outermost (see out , -most ).