RAIL Copy link • RAIL 1. s. tignum transversum (nailed across between two upright posts): rails, railings, septa (plur., general term for fence; with boards, laths, etc.): cancelli (plur.; clathri, trellis-work). 2. v. To enclose with rails, cancellos circumdare alicui rei: or sepire (general term, with or without stipitibus, etc.).