A playwright, often known as a dramatist, is someone who writes plays.
The word "play" comes from the Middle English word pleye, which comes from the Old English words pl, plea, and pla ("play, exercise; sport, game; drama, applause"). The term "wright" refers to a craftsman or a builder who works with his hands in an ancient English dialect (as in a wheelwright or cartwright). It is implied by the combination of the terms that a playwright has "woven" together words, ideas, and other components to create a theatrical form—a play. ) The homophone with the word "write" is just accidental.
A playwright is first mentioned in print in 1605, a full 73 years before the first documented use of the word "dramatist" appears. Ben Jonson is credited with being the first to use the term in a derogatory manner to refer to a simple craftsman who creates works for the theatre stage.