This line is incorrect, as it will always evaluate to true:
elif word[0] == 'a' or 'e' or 'i' or 'o' or 'u':
What you meant to write was:
elif word[0] == 'a' or word[0] == 'e' or word[0] == 'i' or word[0] == 'o' or word[0] == 'u':
You can simplify it by doing:
elif word[0] in 'aeiou':