atomic

Etymology

atom + -ic

adj

1. (physics, chemistry) Of or relating to atoms; composed of atoms; monatomic.
   A stream of atomic hydrogen is emitted.
2. Employing or relating to nuclear energy or processes.
   We built a small atomic bomb in the garage.
   Before the atomic spy Allan Nunn May left Canada to go to London, a treff in London had to be arranged for him and another agent. 1955, David J. Dallin, Soviet Espionage, page 495
3. Infinitesimally small.
   The hairs on a bedbug are almost atomic.
4. Unable to be split or made any smaller.
   1. (programming, of a commit in a VCS) Containing a single change, as opposed to involving numerous unrelated changes.
   2. (logic, of a proposition) Lacking logical operators; unable to be made simpler in logical form.
5. (computing, of an operation) Guaranteed to complete either fully or not at all while waiting in a pause, and running synchronously when called by multiple asynchronous threads.
   In order to avoid race conditions, this operation has to be atomic.
   Whenever possible, use atomic types instead of mutexes.
   It also provides an atomic compareAndSet method (which if successful has the memory effects of both reading and writing a volatile variable) and, for convenience, atomic add, increment, and decrement methods. 2006, Tim Peierls, Brian Goetz, Joshua Bloch, Joseph Bowbeer, Doug Lea, David Holmes, Java Concurrency in Practice, Pearson Education, page 325

noun

1. (computing) An atomic operation.