n.1.The act of retarding, or delaying; retardation.
Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in periodicals archive ?
(4) These infants were left with mental re tardation, developmental delays and damaged motor function.
Education and Training in Mental Re tardation and Developmental Disabilities, 34, 312-317.