since 1975 (earliest usage recorded on this site was 1987)
Scheme is one of the two main dialects of the programming language Lisp. Unlike Common Lisp, the other main dialect, Scheme follows a minimalist design philosophy specifying a small standard core with powerful tools for language extension. Its compactness and elegance have made it popular with educators, language designers, programmers, implementors, and hobbyists, and this diverse appeal is seen as both a strength and, because of the diversity of its constituencies and the wide divergence between implementations, one of its weaknesses.
Scheme was the first dialect of Lisp to choose lexical scope and the first to require compilers to perform tail-call optimization. It was also one of the first programming languages to support first-class continuations. It had a significant influence on the effort that led to the development of its sister, Common Lisp.