- ENIGMA
- Hmmmmmm provokeer
- Riddle
- Puzzle
- Hmmmmmm provoker
- Real poser
- Stumper
- Code broken in the 2014 biopic "The Imitation Game"
- National Puzzlers League newsletter, with "The"
- Nazi's cipher
- Total stumper
- Tough nut to crack
- It's hard to understand
- The National Puzzlers' League's monthly newsletter, with "The"
- Something inscrutable
- Baffler
- Poser
- Mystery
- WWII cipher machine
- Encryption machine of yore
- WWII coding machine
- Riddle relative
- World War II encoding machine
- Brainteaser
- Puzzler
- It's puzzling
- Something of a mystery
- It's something of a mystery
- Mona Lisa's smile, for one
- Inscrutable sort
- Conundrum
- Puzzling person
- Puzzling situation
- Something hard to grasp
- Head-scratcher
- Brain twister
- Puzzlement
- __ Variations: Elgar opus
- Perplexing puzzle
- It's a mystery
- Perplexity
- Challenging riddle
- Tough one to figure out
- Toughie
- Problem
- WWII encryption machine
- Baffling problem
- Puzzling problem
- It's hard to untangle
- Reason to be at sea?
- Hard puzzle
- Challenging puzzle
- Real mystery
- Real puzzle
- The Imitation Game encryption machine
- Mind-boggler
- Real baffler
- Total mystery
- Puzzle or riddle
- Something puzzling
- WWII code machine
- It's inexplicable
- Hard-to-know person
- Baffling puzzle
- Contradictory character
- Tough puzzle
- Perplexing thing
- Something baffling
- It's a puzzlement
- It's hard to fathom
- Closed book
- National Puzzlers' League publication, with The
- It's no no-brainer
- Inscrutable person
- Inscrutable one.
- Sphinxian riddle.
- Propounded by the Sphynx.
- Sphinxian poser.
- Sphinxian problem.
- Stalin's plans.
- Unsolved mystery.
- Anything puzzling.
- Obscure saying.
- Sphinx.
- Baffling person.
- Ambiguous saying.
- Woman's age, for one
- Elgar's variations
- Churchill word for Russia
- Hard nut to crack
- Russia, to Churchill
- Elgar's "___ Variations"
- A puzzlement
- Baffling matter
- Monthly publication of the National Puzzlers' League, with "The"
- Personality that's hard to read
- W.W. II German cipher machine
- Elgar's "____ Variations"
- Complete baffler
- It's mind-boggling
- Perplexer
- Something inexplicable
- Hmm? inducer
- It's not clear
- Knot
- Appropriately named monthly of the National Puzzlers' League, with "The"
- I'm a walking, talking ___: Larry David
- The Imitation Game machine
- Nazi cipher machine broken by the Allies
- The Mona Lisa's smile, e.g.
- Very secretive sort
- Cipher machine of W.W. II
- Sadeness (Part I) electronic band
- Real head-scratcher
- Cracked object of WWII
- Riddle or puzzle
- Mind-boggling puzzle
- Puzzle that's a stumper
- Hard puzzle to figure out
- It's truly puzzling
- Mysterious baffler
- Puzzling riddle
- It's hard to figure out
- Source of bafflement
- Total head-scratcher
- Cryptic mystery
- Hmm provoker
- Ciphering system cracked by Alan Turing
- Hard-to-crack puzzle
- Tough person to understand
- Puzzling sort
- Cryptic puzzle
- Axis enciphering machine
- Inscrutable puzzle
- Mysterious sort
