Use "plenitude" as a subject to signify abundance. For example, "A plenitude of marsh and mire in the countryside made traveling perilous."
Use "plenitude" as a direct object to signify the state of being full. For example, "North Atlantic storms possess a plenitude of salt-driven spray and spindrift."
Use "plenitude" with words that have p sounds when you want alliteration in your sentence. For example, "The tin-pot dictator was remarkable for his plenitude of panicked and impoverished power."
Use "plenitude" as an adjective to indicate that something is characterized by plenitude. For example, "Plenitudinous bubblegum can lead to much pink popping."