echelin X

== Welsh == === Alternative forms === echelin x === Etymology === echelin (“axis”) + X. === Noun === echelin X f (mathematics) x-axis ==== Related terms ==== echelin Y echelin Z === Further reading === Delyth Prys; J.P.M. Jones; Owain Davies; Gruffudd Prys (2006), Y Termiadur: termau wedi'u safoni; standardised terminology‎[1] (in Welsh), Cardiff: Awdurdod cymwysterau, cwricwlwm ac asesu Cymru (Qualifications curriculum & assessment authority for Wales), →ISBN