Can you check the spelling of a word before you play it?

Before you place a word on the board, are you permitted to check the dictionary to make sure it is spelled correctly? My Scrabble club insists you cannot according to the rules of Scrabble.

Also, if you challenge a word on the board, and it is correct, does the challenger lose their turn?

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No - in official Scrabble games, you are not allowed to consult a word reference prior to making your move.

As to whether a challenger can lose their turn when a word turns out to be valid, it depends on where you're playing. The rule that the challenger can lose their turn is called 'double-challenge' and this is used in tournaments and clubs throughout North America. It is also the rule stated on the official Hasbro Scrabble site, which is the Scrabble owner in North America.

Outside of North America, most official Scrabble games are played to a 'single challenge' rule, in which the challenger does not lose a turn, although some tournaments play a compromise rule in which the challenger can lose 5 or 10 points for an incorrect challenge.