1. A polymethine dye or ultraviolet absorber of the formula: ##STR10## where Ar is independently in each occurrence an aromatic nucleus containing from 6 to 10 ring carbon atoms; D is an electron withdrawing group having a cyano, sulfo, or carbonyl group; E is chosen from the class consisting of (i) a heterocyclic nucleus comprises of a five or six membered heterocyclic ring containing at least one heteroatom chosen from the class consisting of nitrogen and chalcogen and (ii) an aminomethine group; L.sup.1 and L.sup.2 are methine groups; and n is the integer 0, 1, or 2.