noun

1. growth in size, esp. by addition or accumulation
2. a growing together of parts normally separate
3. accumulated matter the accretion of earth on the shore
4. a part added separately; addition
5. a whole resulting from such growth or accumulation
6. Law the addition of soil to land by gradual, natural deposits

Etymology: L accretio < accrescere, to increase < ad-, to + crescere, to grow: see crescent