Thunder-clap is a term used to describe a loud and sudden sound associated with lightning. Synonyms for thunder-clap include boom, crash, peal, roar, rumble, and thunderbolt. Boom is a sudden, deep sound that has a booming effect. Crash is a loud and sudden sound that is abrupt and startling. Peal refers to a series of explosive sounds in quick succession. Roar refers to a loud and deep sound, like a lion's roar. Rumble is a low and continuous sound that can be felt as well as heard. Thunderbolt is a loud and sudden bang, like a bolt of lightning striking the ground. Each of these words can be used in place of thunder-clap to describe this powerful weather phenomenon.