as soon as possible.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for a.s.a.p.
as soon as possible
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Word Origin and History for a.s.a.p.
also asap, pronounced either as a word or as four letters; from initial letters of phrase "as soon as possible," 1955, originally U.S. Army jargon.
Online Etymology Dictionary, © 2010 Douglas Harper