tra-, tract-, trac-, -tractive, -traction, -tracting, treat-, trai-

(Latin: drag, draw together; a drawing out or pulling)

treat, treats, treated, treating (verb forms)
treatise
treatment
treaty
turpis contractus
An immoral or iniquitous (unjust, unfair) contract.
—Blacks's Law Dictionary by Henry Campbell Black, M.A.;
West Publishing Co.; St. Paul, Minn.; 1990.