Tough nut to crack synonyms | phrases

Phrases with similar meaning for Tough nut to crack

• closed book

  puzzle, mystery
• hard-line

  stiff
• Gordian knot

  mystery
• mind-boggler

  mystery, brain-teaser
• mind-twister

  mystery
• question mark

  mystery
• single-minded

  stiff
• strait-laced

  stiff
• dead set

  stiff
• set in stone

  stiff, pigheaded
• brain-twister

  brain-teaser
• knotty question

  brain-teaser
• tough proposition

  brain-teaser
• hard-hearted

  pigheaded
• hard-boiled

  pigheaded
• hard-nosed

  pigheaded
• thick-skinned

  pigheaded
• cold fish
• hanging tough
• stiff-necked
• brain-teaser
• hard line
• cold-fish
• locked-in
• not influenced
• with straight face
• iron-hearted
• easy going
• hard as nails
• stony-eyed
• putting on airs
• cool cat
• easy-going
• matter of fact
• on ice
• stiff as a board
• hard-bitten
• hard-handed
• magic number
• skeleton in cupboard
• privileged information
• confidential information
• hard-headed
• brick wall
• iron-fisted
• solid as a rock
• solid as rock
• walking on eggs
• brick-wall
• tough nut