(1):

(n.) The act of producing a hollow or roaring sound; a violent rushing with heavy roar; as, the booming of the sea; a deep, hollow sound; as, the booming of bitterns.

(2):

(a.) Rushing with violence; swelling with a hollow sound; making a hollow sound or note; roaring; resounding.

(3):

(a.) Advancing or increasing amid noisy excitement; as, booming prices; booming popularity.

(4):

(p. pr. & vb. n.) of Boom