concurrent

Etymology

From Middle English concurrent, from Old French concurrent, from Latin concurrēns, present active participle of concurrō (“happen at the same time”), from con- (“with”) + currō (“run”).

adj

1. Happening at the same time; simultaneous.
   Such are the changes which science recognizes in the wire itself, as concurrent with the visual changes taking place in the eye. 1865, John Tyndall, “On Radiation”, in Fragments of Science for Unscientific People, pages 171–2
2. Belonging to the same period; contemporary.
3. Acting in conjunction; agreeing in the same act or opinion; contributing to the same event or effect.
   I join with these laws the personal presence of the king's son, as a concurrent cause of this reformation. 1612, John Davies, Discoverie of the True Causes why Ireland was never entirely subdued
4. Joint and equal in authority; taking cognizance of similar questions; operating on the same objects.
   the concurrent jurisdiction of courts
5. (geometry) Meeting in one point.
6. Running alongside one another on parallel courses; moving together in space.
7. (computing, of code) Designed to run independently, rather than sequentially, using various mechanisms, such as threads, event loops or time-slicing.
   Informally, a concurrent program is one that does more than one thing at a time. […] However, this simultaneity is sometimes an illusion. 2000, Douglas Lea, Concurrent Programming in Java, Addison-Wesley, page 19
   Different concurrent designs enable different ways to parallelize. 2012, Rob Pike, “Concurrency is not Parallelism”, in Waza Conference, San Francisco, page 21
   More precisely, a concurrent algorithm (or concurrent program) is the description of a set of sequential state machines that cooperate through a communication medium, e. g., a shared memory. 2012, Michel Raynal, Concurrent Programming, Springer Science & Business, page 4
   Many languages are dogmatic about the solutions they offer for handling concurrent problems. For example, Erlang has elegant functionality for message-passing concurrency but has only obscure ways to share state between threads. 2018, Steve Klabnik, Carol Nichols, The Rust Programming Language, No Starch Press, page 342

noun

1. One who, or that which, concurs; a joint or contributory cause.
2. One pursuing the same course, or seeking the same objects; hence, a rival; an opponent.
3. One of the supernumerary days of the year over fifty-two complete weeks; so called because they concur with the solar cycle, the course of which they follow.
4. One who accompanies a sheriff's officer as witness.