Nominal TAM is the indication of tense–aspect–mood by inflecting a noun, rather than a verb. In clausal nominal TAM, the noun indicates TAM information about the clause (as opposed to the noun phrase).
Whether or not a particular language can best be understood as having clausal nominal TAM can be controversial, and there are various borderline cases. A language that can indicate tense by attaching a verbal clitic to a noun (such as the -'ll clitic in English) is not generally regarded as using nominal TAM.