Paint is a liquid mixture that can be made into various different colors and applied onto a surface to act as a decorative or protective coating. Such an act is called painting, and one who engages in it is known as a painter.
In 2151, during an inspection of the newly commissioned Enterprise NX-01, Commander Tucker knocked the hull of the ship with an inspection pod. Captain Archer responded by joking that he had scratched the paint. (ENT: "Broken Bow")
In 2153, while Captain Archer was piloting Shuttlepod 1 through an asteroid field, two asteroids collided, sending bits of rubble on to the hull of the small craft. Lieutenant Reed then said that they may need a fresh coat of paint when they return. (ENT: "Impulse")
In 2371, Constable Odo discovered Quark and Morn painting numbers on the backs of Cardassian voles, prepping them for vole fighting, something which was illegal on Deep Space 9. (DS9: "Through the Looking Glass")
In 2375, Captain Benjamin Sisko had an orb-induced vision of Benny Russell, in which Benny had covered the walls of his room in a mental institution with a pencil-written story. Later, Benny almost gave in to Doctor Wykoff's request for him to paint over his writings. (DS9: "Shadows and Symbols")
Later the same year, in an effort to gain possession of a graviton stabilizer, Ensign Nog set up a series of deals, one of which involved the loaning of Captain Sisko's desk. While Nog was away acquiring the stabilizer, Chief O'Brien made a replacement desk for the captain, which was unfinished. O'Brien said he was going to paint it later. (DS9: "Treachery, Faith and the Great River")