In the dungeon of her heart where it had long lain chained is an example of which literary term?

The phrase "in the dungeon of her heart where it had long lain chained" is an example of metaphor. It compares the heart to a dungeon, suggesting that deep emotions or feelings are trapped and confined, evoking a sense of darkness and imprisonment. This imagery enhances the emotional depth of the expression, illustrating the struggle of unexpressed feelings.