import nltk
#nltk.download("words")

from nltk.corpus import words

english_words = set(words.words())

def is_english_word(word):
    return word.lower() in english_words
print(is_english_word("edge"))    # True
print(is_english_word("hello"))   # True
print(is_english_word("edge"))    # True
print(is_english_word("www"))    # False