Two successive lines of rhymed poetry in iambic pentameter, so called for its use in the composition of epic poetry in the 17th and 18th centuries. In neo-classical usage the two lines were required to express a complete thought, thus a closed couplet, with a subordinate pause at the end of the first line. Heroic couplets, which are well-suited to antithesis and parallelism, are also often used for epigrams, such as Pope's:
You beat your pate, and fancy wit will come.
Knock as you please--there's nobody at home.
Sidelight: Poems written in heroic couplets, such as Pope's The Rape of the Lock, are especially subject to the danger of metrical monotony, which poets avoid by variations in their placement of caesuras.
(See also Couplet, Distich, Open Couplet)

This definition is in context to Poetry. See more contextual defintions for Heroic Couplet.