Flame retardant tackifiers are represented by the formula ′ wherein R represents a hydrocarbyl group having 20 carbons and three consecutive fused six-membered rings; and each R2 independently represents an alkyl group having from 1 to 8 carbon atoms. Curable compositions contain a curable binder precursor and at least one of the flame resistant tackifiers. Pressure-sensitive adhesives comprises an elastomer and at least one flame retardant tackifier compound represented by the formula ″ wherein R represents a hydrocarbyl group having 20 carbon atoms and three consecutive fused six-membered rings and each R1 independently represents an alkyl or aryl group having from 1 to 8 carbon atoms.