The original name of Cieneguilla comes from the Spanish word "ciénaga" which means "marsh" or "marshy place". The swampy ground is caused by several streams running across a small flood plain formed by a bend in the Rio Grande. Because the area featured a flat plain with a constant source of water, it was long frequented by the Jicarilla Apache. The village's modern day name of Pilar has been reported to have come from an influential Native American male who lived in the area by the name of Pilar Vigil.
^'The Place Names of New Mexico, Robert Julyan, University of New Mexico Press, 1996
^'New Mexico, A Guide to the Colorful State, Compiled by Workers of the Writers' Program of the Works Projects Administration in the State of New Mexico, University of New Mexico Press, Albuquerque, NM, 1945.
^Pearce, T,M, editor, New Mexico Place Names: A Geographical Dictionary, The University of New Mexico Press, 1965.