BOB - To move gently and vertically, in either a single motion or repeatedly up and down, at or near the surface of a body of water.
MOB - An unruly group of people.
MOO - The characteristic sound made by a cow or bull.
BAM - Representing a loud noise or heavy impact.
BOA - Any of a group of large American snakes, of the genus Boa, including the boa constrictor, the emperor boa of Mexico, and the chevalier boa of Peru.
BOO - A loud exclamation intended to scare someone, especially a child. Usually used when one has been hidden from the victim and then suddenly appeared unexpectedly.
BOMB - An explosive device used or intended as a weapon.
BOOM - To make a loud, resonant sound.
BAMBOO - A plant; a grass of the Poaceae family, characterised by its woody, hollow, round, straight, jointed stem.