Initialism of as soon as possible.
"The manager requested that all reports be submitted asap to meet the deadline."
Alternative spelling of ASAP
In plain English: As soon as possible means doing something right away without waiting any longer.
"Please send me that information asap so we can finish on time."
The phrase "asap" originated in the 1950s within the U.S. military during the Korean War. It was first recorded in Captain Annis G. Thompson's 1954 book The Greatest Airlift, where it meant "as soon as militarily possible."