symmetric group
group of bijective automorphisms of a set, also called bijective group: the group of bijections on a set (the group of all its permutations), whose group operation is function composition
en-US/sɪˈmɛtɹɪk ˈɡɹup/
en-GB/sɪˈmɛtɹɪk ˈɡɹuːp/