What two-letter word for “cindery lava” would be the first acceptable Scrabble word on an alphabetical list?

aa is the word and it means rough

Learning words like AA (rough, cindery lava), XI (Greek letter) and OE (Faeroe Islands whirlwind) will allow you to make plays all over the board. According to the "Official Scrabble Player's Dictionary" (OSPD), there are 96 of these permissible combinations -- but three quarters of them, like AB and ID, you probably already know.
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