underdrain

noun

1. a drain placed beneath the surface of cultivated fields, streets, etc.

verb (used with object)

2. to equip or supply with an underdrain or underdrains.

noun (ˈʌndəˌdreɪn)

1. a drain buried below agricultural land

verb (ˌʌndəˈdreɪn)

2. to bury such drains below (agricultural land)