Meaning

noun a small discrete mass of solid or liquid matter that remains individually dispersed in gas or liquid emissions (usually considered to be an atmospheric pollutant)

adjective composed of distinct particles

originFrom New Latin particulātus (“divided into small parts”) (also particulāta (“small parts”), from its neuter plural), from Classical Latin particula (“particle”), from pars (“part, piece”) + -cula (diminutive suffix), + -ātus (-ate). The verb is probably independently from the adjective rather than from Etymology 2.

Etymology from Wiktionary, CC BY-SA 3.0