Ystrodur, n. the frame work of a saddle, a packsaddle
Ystrodwm, n. a round-about
Ystrwy, n. what passes through
Ystrwyad, n. a forming a passage
Ystrwyo, v. to pass through
Ystrwytho, v. to saturate
Ystrych, n. what forms a scope
Ystrychu, v. to form a scope
Ystryd, n. a way, a street
Ystrym, n. a main stream or current; a channel