in the eleventh place; used to introduce the eleventh point in a series of arguments or statements.
From eleventh (the ordinal number) plus -ly (making it an adverb). The -ly suffix converts adjectives into adverbs indicating manner or sequence.
Writers almost never use 'eleventhly' because it sounds awkward—most people stop listing at 'tenthly' or jump straight to 'finally,' making this one of English's most abandoned adverbs.
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