There are 43 4-letter words that start with 'bu'.
Note: These 43 4-letter words that start with 'bu' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with bur, bul, but, bus, bun, buc, bum, bug, bud, buf, bub, buz, bui, buo, buy, buh, bup, bux, buq.
3-letter words start with 'bu' (9)