in music, adult male alto voice, either natural or falsetto. In England the word generally refers to a falsetto alto rather than a high tenor. Some writers reserve the term countertenor for a naturally produced voice, terming the falsetto voice a male alto.

Derived from the Renaissance contratenor altus, abbreviated to contratenor (countertenor) or altus (alto), the term countertenor was originally applied to an alto part as well as to the voice or the instrument taking this part (see also tenor). Although the falsetto voice lost favour in the rest of Europe during the 18th century, the tradition was preserved in England in the cathedral choirs. In the 20th century the solo countertenor voice was successfully revived and, although it remains associated principally with the performance of Renaissance and Baroque music, several modern composers—notably Benjamin Britten—have written for it.