Name a chess term

The rarest possible answer — almost no player finds it.

• Novotny— A study idea where you sacrifice a piece on the exact square where two enemy pieces cross, jamming both at once. Composers adore it.

Genuinely obscure. Most players never think of it.

• 2700 club
• Abort
• Adjournment
• Adjudication
• Advance Variation
• Advantage
• Alapin Variation
• Albin Countergambit
• Alekhine's Defense
• Alekhine's gun
• Analysis
• Anastasia's mate
• Anderssen's mate
• Annotation
• Announced mate
• Antichess
• Antipositional
• Arabian mate
• Arbiter
• Artificial castling
• Atomic chess
• Attack
• Averbakh Variation
• Babson task
• Bad bishop
• Balestra mate
• Bare king
• Barnes Opening
• Basque chess
• Battery
• Belgrade Gambit
• Benko Gambit
• Benoni Defense
• Berlin Defense
• Berserk
• Bind
• Bird's Opening
• Blackburne's mate
• Blackmar-Diemer Gambit
• Blind pigs
• Blindfold chess
• Boden's mate
• Bogo-Indian Defense
• Bongcloud
• Book move
• Botez Gambit
• Botvinnik System
• Breakthrough
• Breyer Variation
• Brilliancy
• Budapest Gambit
• Bughouse
• Building a bridge
• Bust
• Bye
• Caissa
• Calculation
• Cambridge Springs
• Can opener
• Candidate Master
• Candidate move
• Castling rights
• Catalan
• Centipawn
• Centralization
• Cheapo
• Chess blindness
• Chess clock
• Chess engine
• Chess problem
• Chess960
• Chessboard
• Chessmen
• Chigorin Defense
• Chop wood
• Closed game
• Coffeehouse
• Colle System
• Collinear move
• Compensation
• Composer
• Computer move
• Connected passed pawns
• Consolidation
• Cook
• Corner mate
• Correspondence chess
• Corresponding squares
• Counterattack
• Countergambit
• Counterplay
• Country move
• Cow Opening
• Cramped
• Crazyhouse
• Cross-check
• Crosstable
• Damiano's mate
• Danish Gambit
• Dark-squared bishop
• David and Goliath mate
• Dead position
• Defense
• Demonstration board
• Descriptive notation
• Desperado
• Directmate
• Domination
• Double attack
• Doubled rooks
• Dovetail mate
• Dragon
• Draw by agreement
• Draw death
• Draw odds
• Drawish
• Duck chess
• Duplex
• Dutch Defense
• ECO
• Elephant Gambit
• En prise
• Endgame study
• Englund Gambit
• Epaulette mate
• Equalize
• Evaluation
• Evans Gambit
• Exchange Variation
• Fairy chess
• Fantasy Variation
• FEN
• FIDE Master
• Fingerfehler
• Fish
• Fivefold repetition
• Flank
• Flank opening
• Fog of war
• Forced mate
• Forced move
• Fortress
• Four Knights Game
• Frontier line
• Gardez
• Glicko
• Good bishop
• Grandmaster draw
• Grasshopper
• Greco's mate
• Greek gift
• Grob's Attack
• Grotesque
• Grunfeld
• Half-open file
• Halloween Gambit
• Hand and brain
• Hanging pawns
• Hauptturnier
• Hedgehog
• Helpmate
• Hippopotamus Defense
• Hole
• Hook mate
• Horde
• Hypermodern
• ICBM Gambit
• Icelandic Gambit
• Illegal move
• Imbalance
• Inaccuracy
• Indian Defense
• Insufficient material
• Interpose
• Irregular opening
• J'adoube
• Key move
• Key square
• Kibitz
• Kick
• Kill box mate
• King hunt
• King of the Hill
• King safety
• King walk
• King's Fianchetto Opening
• King's Indian Attack
• King's Pawn Opening
• Knight's tour
• Kotov syndrome
• Kriegspiel
• Ladder mate
• Latvian Gambit
• Legal's mate
• Light-squared bishop
• Liquidation
• Lolli's mate
• Long diagonal
• Loose piece
• Lucena position
• Luft
• Main line
• Major piece
• Mar del Plata
• Maroczy Bind
• Marshall Attack
• Master
• Match
• Mating net
• Max Lange's mate
• Mayet's mate
• Meran Variation
• Miniature
• Minor piece
• Mobility
• Model mate
• Modern Defense
• Morphy's mate
• Moscow Variation
• Mouse slip
• Move order
• Mysterious rook move
• National Master
• Nightrider
• Nimzo-Indian
• Nimzowitsch Defense
• Nimzowitsch-Larsen Attack
• Norm
• Novelty
• Octopus
• Odds
• Old Indian Defense
• Open game
• Opera mate
• Opposite castling
• Outpost
• Outside passed pawn
• Over the board
• Overprotection
• Owen's Defense
• Panov Attack
• Patzer
• Pawn break
• Pawn center
• Pawn grabber
• Pawn island
• Pawn majority
• Pawn race
• Petrov Defense
• PGN
• Philidor Defense
• Philidor position
• Pillsbury's mate
• Pirc Defense
• Plachutta
• Ply
• Poisoned pawn
• Ponziani Opening
• Position
• Positional play
• Post mortem
• Premove
• Prepared variation
• Principle of two weaknesses
• Priyome
• Proof game
• Prophylaxis
• Protected passed pawn
• Pure mate
• Queen's Gambit Accepted
• Queen's Gambit Declined
• Queen's Indian Defense
• Queen's Pawn Opening
• Quickplay finish
• Quiet move
• Racing kings
• Raking bishops
• Recapture
• Refutation
• Remis
• Removing the defender
• Repertoire
• Reti Opening
• Reti's mate
• Retrograde analysis
• Romantic chess
• Rook lift
• Rossolimo Variation
• Royal fork
• Samisch Variation
• Sandbagging
• Scalp
• Score sheet
• Scotch Game
• Second
• Selfmate
• Seriesmover
• Seventy-five move rule
• Sharp
• Simul
• Sitzfleisch
• Skittles
• Slav Defense
• Smith-Morra Gambit
• Sofia rules
• Sokolsky Opening
• Sortie
• Spite check
• Squeeze
• St. George Defense
• Stafford Gambit
• Staircase maneuver
• Staunton
• Stem game
• Stonewall
• Sudden death
• Suffocation mate
• Sveshnikov Variation
• Swallow's tail mate
• Swindle
• Swiss system
• Tabiya
• Tablebase
• Takeback
• Tarrasch Defense
• Tarrasch rule
• Tension
• Theory
• Threat
• Three-check
• Tiebreak
• Time pressure
• Torre Attack
• Transposition
• Trapped piece
• Trebuchet
• Triangle mate
• Triangulation
• Tripled pawns
• Troitsky line
• Trompowsky Attack
• Twin
• Two Knights Defense
• Undermining
• USCF
• Valve
• Vienna Game
• Vukovic mate
• Waiting move
• Ware Opening
• Weak square
• Winawer Variation
• Windmill
• Wing Gambit
• Woman Candidate Master
• Woman FIDE Master
• Woman Grandmaster
• Woman International Master
• Woodpusher
• Wrong bishop
• Zaitsev Variation
• Zeitnot
• Zwischenschach

Uncommon — only a minority of players land here.

• Algebraic notation
• Armageddon
• Back rank mate
• Backward pawn
• Bishop pair
• Blockade
• Bullet
• Caro-Kann
• Center
• Classical
• Clearance
• Combination
• Decoy
• Deflection
• Development
• Diagonal
• Discovered attack
• Discovered check
• Doubled pawns
• Elo
• English Opening
• Exchange
• Fianchetto
• FIDE
• Fifty move rule
• Flag
• French Defense
• Fried Liver Attack
• Hanging piece
• Increment
• Initiative
• International Master
• Isolated pawn
• Italian Game
• King's Gambit
• King's Indian Defense
• Kingside
• London System
• Material
• Minority attack
• Najdorf
• Notation
• Open file
• Opposite-colored bishops
• Opposition
• Overloading
• Passed pawn
• Pawn chain
• Pawn storm
• Pawn structure
• Perpetual check
• Queenside
• Rapid
• Rating
• Ruy Lopez
• Scandinavian Defense
• Smothered mate
• Space
• Tempo
• Threefold repetition
• Time control
• Touch move
• Trap
• Underpromotion
• Variation
• X-ray
• Zwischenzug

A solid, middling pick shared with plenty of other players.

• Bishop
• Blitz
• Blunder
• Capture
• Double check
• Draw
• En passant
• Endgame
• File
• Fool's mate
• Fork
• Gambit
• Grandmaster
• King
• Knight
• Middlegame
• Opening
• Pawn
• Pin
• Promotion
• Queen
• Queen's Gambit
• Rank
• Resign
• Rook
• Sacrifice
• Scholar's mate
• Sicilian Defense
• Skewer
• Strategy
• Tactics
• Zugzwang

The most common answer on the board.

• Castling
• Check
• Checkmate
• Stalemate