Rule combination can contribute to morphological simplicity. Synchronically, rule combinations (like word combinations) are sometimes stored as formulaic units, and this fact contributes to a morphological system’s processing simplicity, since accessing a stored rule combination directly is simpler than decomposing that combination into its component rules for separate lookup. Stored, formulaic rule combinations may also contribute to diachronic simplifications of a language’s morphology, since they are the locus of reanalyses that may eventuate in “affix telescoping,” the development of a rule combination into a simple rule. But affix telescoping is not a monolithic phenomenon; it involves the reduction of a rule combination’s combinatory transparency along at least four dimensions. Thus, it is possible to find rule combinations that are progressing toward reanalysis as simple rules without yet having reached the point of reanalysis.