Synonyms: Cyclobuta[1,2-d:4,3-d']dipyrimidine-2,4,5,7(3H,6H)-tetrone,1,4a,4b,8,8aa,8ba-hexahydro-4aa,4ba-dimethyl- (8CI);Cyclobuta[1,2-d:4,3-d']dipyrimidine-2,4,5,7(3H,6H)-tetrone,hexahydro-4a,4b-dimethyl-, (4aa,4ba,8aa,8ba)-; Cyclobutadithymine; Thymine dimer; Thymine, dimer, cis-syn-;Thymine-thymine; cis-syn-Thymine dimer