Papañca is conceptual proliferation, the elaboration by which a sense experience is overlaid with thoughts, judgements and the sense of I, giving rise to conflict and suffering. The Honeyball Sutta traces the process. Its stilling, nippapañca, is a name for nirvāṇa.
Papañca
Proliferation: the mind’s tendency to spin concepts and stories out of simple experience.
Also: Papanca, prapanca, proliferation