I'm trying to enter antonyms by part of speech into a database (for natural language processing) and have run into a problem with "indoors" vs "outdoors". One dictionary lists parts of speech for "outdoors" as adverb, noun, and adjective; another, as just adverb and adjective; a third, as adverb and noun.
The first dictionary lists "indoors" only as adverb; the second, as adverb and adjective; the third, only as adverb. None of them list "indoors" as a noun.
I plan on ignoring the dictionaries and entering the words as antonyms of each other as nouns, adjectives and adverbs, but before I do...
Is there really some reason that "indoors" can't be a noun? (E.g.: "My wife loves the outdoors, but I love the indoors.")