Arabic grammarians typically use the root فعل f-ʿ-l to indicate the particular shape of any given element of a verbal paradigm. As an example, the form يتكاتب yutakātabu 'he is corresponded (with)' would be listed generically as يتفاعل yutafāʿalu, specifying the generic shape of a strong Form VI passive verb, third-person masculine singular present indicative.