The present participle of alphabetize; arranging something in alphabetical order or teaching someone the alphabet.
From 'alphabet' + the verb-forming suffix '-ing.' This gerund form emerged as 'alphabetize' became a standard verb in English during the 19th century.
Librarians spend huge chunks of their lives 'alphabeting' things—and they're kind of obsessive about it because just one misfiled book can disappear into the stacks forever, which is why they invented entire systems to check their work.
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