Medical Definition of double helix
: a helix or spiral consisting of two strands in the surface of a cylinder that coil around its axis; especially : the structural arrangement of DNA in space that consists of paired polynucleotide strands stabilized by cross-links between purine and pyrimidine bases—compare alpha-helix, watson-crick model
Seen and Heard
What made you want to look up double helix? Please tell us where you read or heard it (including the quote, if possible).