insanely

UK: /ɪnˈseɪnli/

WordReference Random House Learner's Dictionary of American English © 2026

in•sane /ɪnˈseɪn/   adj. 

1. Psychiatry [not in technical use] mentally unsound; mad.
2. of or characteristic of the mentally deranged:
   insane actions.
3. utterly senseless;
   irrational;
   foolish:
   You're insane if you think you can jump off that bridge and live.

in•sane•ly, adv. 
in•sane•ness, n. [uncountable]
in•san•i•ty /ɪnˈsænɪti/  n. [uncountable] See -san-.

WordReference Random House Unabridged Dictionary of American English © 2026

in•sane  (in sān′), adj. 

1. not sane;
   not of sound mind;
   mentally deranged.
2. of, pertaining to, or characteristic of a person who is mentally deranged:
   insane actions; an insane asylum.
3. utterly senseless:
   an insane plan.

• Latin insānus. See in-³, sane
• 1550–60

in•sane′ly, adv. 
in•sane′ness, n. 
Synonyms

• 1. demented; lunatic, crazed, crazy; maniacal.
• 3. foolish, irrational. See mad.