To grow or increase gradually by accumulation or coalescence. Over time, small particles in space accrete to form larger celestial bodies.
To come together under the influence of gravitation to form a larger mass. The dust and gas in the nebula began to accrete, eventually forming a new star.
To cause (something) to grow or come together by gradual accumulation or coalescence. Centuries of limestone-rich water accreted thick layers of calcite onto the cave walls.