2-letter words that start with O are 2 and 3-letter words that start with O are 5. 4-letter words that start with O are 5 and 5-letter words that start with O are 4. 6-letter words that start with O are 6 and 7-letter words that start with O are 16. 8-letter words that start with O are 8 and 9-letter words that start with O are 8. 10-letter words that start with O are 5 and 11-letter words that start with O are 4. 12-letter words that start with O is 1 and 13-letter words that start with O is 1. 14-letter words that start with O is 1. Total start with O are 66.