What is a couplet in which the second line is incomplete and relies on succeeding material for completion called?

A couplet in which the second line is incomplete and relies on succeeding material for its completion is referred to as an open couplet. This type of couplet does not express a complete thought within its two lines; instead, it leaves a sense of anticipation, encouraging the reader to continue into the following lines to grasp the full context or meaning. This stylistic choice can create a more dynamic reading experience, as the reader must engage with the text further to resolve the thought.

In contrast, a closed couplet presents a complete idea or thought within its two lines, ensuring that the reader does not need to go beyond those lines for clarity. The heroic couplet specifically refers to rhymed pairs of iambic pentameter lines that are often used in epic poetry, while an epic couplet is similar but typically tied to a grand narrative style. Each of these alternatives serves different poetic functions, emphasizing complete thoughts or specific structures rather than the open-endedness associated with an open couplet.