The *(term) for a *(programming language) designed for a special purpose, usually within some commercial field of application, although such a language can be made for practically any domain.

There is a separate strand of research just to improve the ability to develop efficient and usable domain-specific languages.

Some research:
<ul class="links">
<li>_("Designing and Using Combinators: The Essence of Functional Programming"|http://www.math.chalmers.se/~rjmh/Combinators/), a graduate course by John Hughes on combinator libraries _(aka) Domain Specific Embedded Languages.</li>
<li>_("Domain-Specific Languages"|http://compose.labri.fr/documentation/dsl/) at _("IRISA/INRIA - LABRI, COMPOSE Project"|http://compose.labri.fr) [_(MIA)?].</li>
<li>_("Functional Domain-Specific Languages "|http://www-sal.cs.uiuc.edu/~kamin/dslresearch.html).</li>
<li>_("Series of seminars"|http://www.hh.se/staff/vero/DSL/) Domain Specific Languages at _("Halmstad University"|http://www.hh.se/english/index.htm).</li>
<li>_("USENIX - Conference on Domain-Specific Languages"|http://www.usenix.org/events/bytopic/dsl.html).</li>
<li>_(LtU) has a _("section on DSL's"|http://lambda.weblogs.com/newsItems/viewDepartment$DSL).</li>
<li>A _("wiki on DSLs"|http://www.cwi.nl/htbin/dsl/wiki/wiki) at _("CWI"|http://www.cwi.nl/).</li>
<li>_(The Promise of DSLs| http://www.cs.yale.edu/homes/hudak-paul/hudak-dir/dsl/), a webbed presentation.</li>
</ul>