Somersault: A leap or spring in which a person turns heels over head in the air and alights on his feet; esp. such a feat as performed by acrobats or tumblers; a pitchpoll. Hence, a turning over in this fashion; a complete overturn, upset, etc. ——Oxford English Dictionary

Somersault: a movement in which someone rolls or jumps forwards or backwards so that their feet go over their head before they stand up again.——Longman Dictionary of Contemporary English  @zh

身体向下翻转而后恢复原状。—《汉语大词典》  @zh

翻跟头  @zh