A matter of the utmost importance.
Worked every day to the utmost of her abilities.
The utmost tip of the peninsula.
The need for food when you are starving is an example of something that would be described as being of the utmost importance.
Origin of utmost
- Middle English from Old English ūtmest ūt out ud- in Indo-European roots -mest -most
From American Heritage Dictionary of the English Language, 5th Edition
- Old English ut (“out") + -most