Merriam-Webster's Word of the Day for June 26, 2026 is:

symbiosis • \sim-bee-OH-sis\  • noun

Symbiosis is a formal word that refers to a relationship between two people or groups that work with and depend on each other. In biology, symbiosis refers to the relationship between two different kinds of living things that live together and depend on each other.

// The new playground is the result of symbiosis between multiple stakeholders, including residents, donors, and town officials.

// The bacteria exist in symbiosis with the plant’s roots.

See the entry >

Examples:

“In the old days, which weren’t that long ago ... there was that ritual moment when a rock ‘n’ roll idol, in the midst of delivering a classic anthem, would point the mic away from himself and into the arena, indicating that it was time for the audience to take over and sing the lines. It might be Springsteen doing ‘Thunder Road,’ or Madonna doing ‘Holiday.’ ... The loving symbiosis of pop star and pop audience doesn’t get much more reverent than that.” — Owen Gleiberman, Variety, 7 May 2026

Did you know?

Symbiosis was adopted by the scientific community in the late 1800s, coming ultimately (via German) from the Greek symbíōsis, meaning “living together, companionship.” Of course, there are a lot of ways to live together and, accordingly, several flavors of symbiosis. When a biological symbiosis between two organisms is mutually beneficial, it is termed mutualism. For example, oxpeckers are birds so named because they “peck” ticks off of infested cattle and wild mammals, a likely satisfying arrangement for both parties, and textbook mutualism. When one organism lives off another at the other’s expense, however (as, for one icky instance, head lice do), it’s called parasitism. If only parents of elementary school students could call upon an equivalent of oxpeckers to engage in mutualistic symbiosis when the need arose, but alas.