Symbiotic is an adjective that means characterized by a cooperative, interdependent relationship.
The Greek word symbiosis (sim be OH sis) is a noun that refers to ‘a living together.’ Our word of the day is the adjective version. It entered English in the late 19th century and was mainly used in a biological context. For example two animals with a mutually beneficial relationship were said to have a symbiotic relationship. By the early 20th century, the word came to be used in contexts that had nothing to do with biology.
Now that Susan needs Ross’s help to get around, the two of them have a symbiotic relationship. Before that, their union was always one-sided.