Blockheadedness is valid Scrabble Word

Is blockheadedness a scrabble word?
Official Scrabble Players Dictionary NO
Official Tournament and Club Word List NO
Collins Scrabble Words YES
Is blockheadedness valid Words with Friends?
Words with Friends NO

Definitions for BLOCKHEADEDNESS in dictionary:

Words related to BLOCKHEADEDNESS

blockhead21
Find what other words can be done using letters: "blockheadedness"
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