noun

1. A pair of lines with rhyming end words.

2. A pair of one-way streets which carry opposing directions of traffic through gridded urban areas.

   “5th Street is one-way west only and 6th Street is one-way east only. Together, they form a couplet in Downtown Los Angeles.”

3. A pair of two mutually exclusive choices in a dichotomous key.

Synonyms: one-way pair