for the life of one

for the life of (one)

Despite one's best efforts; to any degree whatsoever. Often used in negative constructions. For the life of me, I can't remember where I left my keys! She couldn't understand for the life of her why people were so obsessed with celebrity gossip.
See also: life, of
Farlex Dictionary of Idioms.

for the life of one

Although trying hard, as in I can't for the life of me remember his name. This expression is always used hyperbolically, that is, one's life is not at all endangered. [Late 1700s]
See also: life, of, one
The American Heritage® Dictionary of Idioms by Christine Ammer.
See also:
  • mean (something) by (something)
  • mean by
  • change (one's) stripes
  • change one's stripes
  • change one's stripes/spots, cannot
  • a month of Sundays
  • take it with (one) (when one goes)
  • take it with one
  • anytime soon
  • have it both ways