Kalapa (atomism)
Kalapa or rupa-kalapa (from Sanskrit rūpa "form, phenomenon" and kalāpa "bundle") is a term in Theravada Buddhist phenomenology for the smallest units of physical matter, said to be about 1/46,656th the size of a particle of dust from a wheel of chariot. Kalapas are not mentioned in the earliest Buddhists texts, such as the Tripitaka, but only in the Abhidhammattha-sangaha, an Abhidhamma commentary dated to the 11th or 12th century, and as such not part of common Theravada doctrine.