1 extreme /ɪkˈstriːm/ adjective
1 extreme
Learner's definition of EXTREME
: very great in degree
[more extreme; most extreme] : very serious or severe
[more extreme; most extreme] : very far from agreeing with the opinions of most people : not moderate
always used before a noun : in the farthest possible position
: unusual and dangerous
always used before a noun, US : involved in an unusually dangerous sport : competing in an extreme sport

go to extreme lengths

see length

— extremely

2 extreme /ɪkˈstriːm/ noun
plural extremes
2 extreme
plural extremes
Learner's definition of EXTREME
: either one of two opposite conditions, feelings, positions, etc., that are thought of as being far from what is normal or reasonable
often plural
: an amount or degree that is far beyond what is normal or reasonable
◊ If you carry/take (something) to extremes or go to extremes, you do much more than most people would consider reasonable or normal.

in the extreme

: to the greatest possible degree used to make a statement more forceful