Trefn, n. system, order, method
Trefnau, utensils, implements
Trefnedigaeth, n. adjustment
Trefniad, n. an ordering, an arranging
Trefniant, n. system, regulation
Trefnid, n. arrangement
Trefnidaeth, management
Trefnidedd, n. economy
Trefnido, v. to manage
Trefnidol, a. economical