dog
pontoon
"Yellow" is a 6-letter word with 3 vowels (e, o, and o) and 3 consonants (y, l, and w).
off
oil
Owl is an animal. It is a 3 letter word.
another
You don't. The letter O is a letter, not a word. The word "oh" is a word but it does not stand for the letter O.
zoo
There are none. Not even a 3 letter word
Oxblood is a 7 letter word with 3 o's. It is a color. It is a dark shade of red that resembles burgundy.
ovation
That might be OMG.