rill / rille [rɪl]
rill - n. & v. – n. – 1. a type of very thin cloth; 2. a small stream; 3. a trickle; 4. a narrow groove especially for planting seed; v. – 1. to make a trickle with liquid; 2. to plant in a small furrow
rille - n. – Astron. a trench like formation – a long, narrow channel on the lunar surface or other satellite or planet, thought to have been formed by surface lava flows or collapsed lava tubes