epithet
n
adjective or descriptive phrase that refers to the character or most important quality of sb/sth eg Alfred the Great, Attila the Hun (表示某人[某事物]性格或最主要特性的)修饰词或描述性短语(如阿尔弗烈德大王, 匈奴王阿提拉).
There has long been a superstition among mariners that porpoises will save drowning men by pushing them to the surface, or protect them from sharks by surrounding them in defensive formation.