Term for a type of relationship that two parties benefit from

Looking for a term, phrase or idiom that best describes a special type of relationship between two parties, not necessarily humans, in which both gain unprecedented benefits. However, such advantages could not be acquired without the relationship; they can continue their own ways without that. In fact, the relationship will add something invaluable.

The desired word should complete such a sentence : There is a ---- relationship between concept A and B.


There is a relationship of synergy/ (synergistic relationship) between concept A and concept B working together.

A synergistic relationship is one where two parties, or things, working together, are able to produce a result that is greater than the sum of what they can each do individually.

It is perhaps OED sense 3 of synergy which seems relevant here:

  1. Any interaction or cooperation which is mutually reinforcing; a dynamic, productive, or profitable affinity, association, or link.

1957 R. B. Cattell Personality & Motivation xvii. 791 Immediate synergy through group membership..expresses the energy going into the group life as a result of satisfaction with fellow members.

1981 Economist 28 Nov. 19/2 Others, through mergers (eg, research houses into retail brokerage houses), have demonstrated that there is something to be said for synergy.

1990 B. Burrough & J. Helyar Barbarians at Gate xvi. 436 They had nothing in common. No synergy. No flow of ideas or people back and forth.

2006 Wall St. Jrnl. 27 Nov. r4/1 A software and hardware ‘ecosystem’ that tries to mimic the successful synergy between iTunes software and iPod gadgets

.


A symbiotic relationship is one where each party provides benefits to the other that they cannot get on their own:

b : characterized by or being a close, cooperative, or interdependent relationship
Sigal's study … illustrates how reporters' constant need for news and how government officials' need for publicity and favorable coverage for their agencies combine into a symbiotic relationship between Washington reporters and officials. —Charles R. Wright
definition from m-w.com


"Mutually beneficial" is the term used almost exclusively, particularly when talking about any kind of interpersonal, business, or diplomatic relationship/partnership. (As an aside, 'Partnership' also implies a positive outcome for all parties)

The other answers here are very accurate in a scientific or academic sense, but practically not used in any other setting.

It would be very unusual and quite jarring to see/hear them in any other kind of speech or writing (casual or formal, fiction or non-fiction).


I suggest the phrase "win-win" describes what you are looking for; see the Cambridge Dictionary definition.

A win-win situation or result is one that is good for everyone who is involved:

Flexible working hours are a win-win situation for employers and employees.

And win-win implies a relationship or trade of goods or services that benefits all parties and wouldn't exist with out the relationship.

UPDATE:

Reading through the other answers, I will also add that win-win is more colloquial and avoids some of the issues raised by others.


Reciprocal

I would use reciprocal if both parties give to each other in order to receive the benefits the other provides. It has a sort of "quid pro quo" connotation.

Definition of reciprocal

  1. a : inversely related : opposite

    b : of, constituting, or resulting from paired crosses in which the kind that supplies the male parent of the first cross supplies the female parent of the second cross and vice versa

  2. shared, felt, or shown by both sides

  3. serving to reciprocate : consisting of or functioning as a return in kind; the reciprocal devastation of nuclear war

  4. mutually corresponding agreed to extend reciprocal privileges to each other's citizens

    b : marked by or based on reciprocity; reciprocal trade agreements

merriam-webster.com