Relating to, concerning, or outside the scope of a dictionary's standard entries and definitions.
From 'extra-' (outside) + 'dictionary' + '-ary' suffix. This is a constructed word describing things beyond typical lexicographic coverage, created by analogy with other 'extra-' prefix words.
This word is practically unattested in any corpus—it's a perfect example of how English can theoretically create infinite words through prefixes, but society only 'adopts' the ones that solve real communication problems.
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