What is the term for the specific pairing of bases in DNA discovered by Watson and Crick?

The term for the specific pairing of bases in DNA is complementary base pairing. In DNA, adenine pairs with thymine, while guanine pairs with cytosine, creating the matching relationships that help explain how genetic information is copied.

These pairings are held together by hydrogen bonds: adenine and thymine form two, while guanine and cytosine form three. The bases therefore match in a precise way across the two antiparallel strands, while the sugar-phosphate backbones remain on the outside of the helix.

Watson and Crick used this complementarity in their 1953 double-helix model. It also explains DNA replication: when the strands separate, each can serve as a template for a new complementary strand. A common mix-up is treating “double helix” as the answer; that describes DNA's overall shape, whereas complementary base pairing describes the molecular matching rule. “Hydrogen bonding” is the interaction holding the pairs together, not the pairing term itself.