Words.word() from nltk corpus seemingly contains strange non-valid words

This code loops through every word in word.words() from the nltk library, then pushes the word into an array. Then it checks every word in the array to see if it is an actual word by using the same library and somehow many words are strange words that aren't real at all, like "adighe". What's going on here?

import nltk
from nltk.corpus import words

test_array = []
for i in words.words():
    i = i.lower()
    test_array.append(i)

for i in test_array:
    if i not in words.words():
        print(i)

Solution

I don't think there's anything mysterious going on here. The first such example I found is "Aani", "the dog-headed ape sacred to the Egyptian god Thoth". Since it's a proper noun, "Aani" is in the word list and "aani" isn't.

According to dictionary.com, "Adighe" is an alternative spelling of "Adygei", which is another proper noun meaning a region of Russia. Since it's also a language I suppose you might argue that "adighe" should also be allowed. This particular word list will argue that it shouldn't.