1. level best, maximum, utmost, uttermost

the greatest possible degree

Example Sentences:
'he tried his utmost'

• level best
• maximum
• uttermost

2. extreme, utmost, uttermost

of the greatest possible degree or extent or intensity

Example Sentences:
'extreme cold'
'extreme caution'
'extreme pleasure'
'utmost contempt'
'to the utmost degree'
'in the uttermost distress'

• extreme
• uttermost

3. last, utmost

highest in extent or degree

Example Sentences:
'to the last measure of human endurance'
'whether they were accomplices in the last degree or a lesser one was...to be determined individually'

• last

4. farthermost, farthest, furthermost, furthest, utmost, uttermost

(comparatives of far') most remote in space or time or order

Example Sentences:
'had traveled to the farthest frontier'
'don't go beyond the farthermost (or furthermost) tree'
'explored the furthest reaches of space'
'the utmost tip of the peninsula'

• farthermost
• farthest
• furthermost
• furthest
• uttermost