irrigation

transitive verb irrigated -·gat′ed, irrigating -·gat′·ing

1. to refresh by or as by watering
2. to supply (land) with water by means of ditches or artificial channels or by sprinklers
3. Med. to wash out or flush (a cavity, wound, etc.) with water or other fluid

Etymology: < L irrigatus, pp. of irrigare, to bring water to or upon < in-, in, to, upon + rigare, to water, moisten: see rain