deoxyribonucleic acid UK /di.ɒk.sɪˌɹaɪ.bəʊ.njuːˈkleɪ.ɪk ˈæ.sɪd/US /di.ɔk.siˌɹaɪ.boʊ.nuːˈkleɪ.ɪk ˈæ.sɪd/ noun1 •A nucleic acid found in all living things (and some non-living things such as certain viruses) which consists of two polynucleotide chains that coil around each other to form a double helix; encoded in its structure are genetic instructions for development, functioning, growth, and reproduction. formsdeoxyribonucleic acids