Iambic Pentameter
A line of verse with five metrical feet, each an unstressed syllable followed by a stressed one.
Iambic pentameter is the backbone of much English poetry, its da-DUM rhythm repeated five times per line. Writers favor it because its heartbeat cadence closely mirrors natural English speech while still feeling elevated. Shakespeare’s plays and the English sonnet both rely on it.
Example
Most of the play’s dialogue rides this five-beat line, so when a character’s speech falls out of rhythm it signals disorder or unraveling.
Macbeth · William Shakespeare