metaphor which is drawn-out beyond the usual word or phrase to extend throughout a stanza or an entire poem, usually by using multiple comparisons between the unlike objects or ideas. Sidelight: Tennyson's " Crossing the Bar," demonstrates the effectiveness of this device: metaphorically, he compares a sandbar in the Thames River over which ships cannot pass until high tide, with the natural time for completion of his own life's journey from birth to death.(See also Conceit)
is where the same metaphor is continued over several lines or through the entire piece. Example: In Othello, Iago and Roderigo's interaction has an extended metaphor of money (meaning patience and strength) over several lines.
An extended metaphor, also called a conceit, is a metaphor that continues into the following sentences. An extended metaphor is also a metaphor developed at great length, occurring frequently in or throughout a work.