Definition of ‘Pied Piper’ German Legend a musician who rids Hamelin of its rats by leading them with his piping to the river, where they drown: in revenge for not being paid, he pipes the village children to a mountain, where they disappear : in full Pied Piper of Hamelin 2. [also p- p-] a leader whom people willingly follow, often, specif., one who leads others into danger or trouble by means of elaborate, false promises