The tenor bassoon or tenoroon is a member of the bassoon family of double reed woodwind instruments. Many debates have been had on the nomenclature of the smaller bassoons. All small bassoons have at one time or another been called fagottino (pl. fagottini), but this term is historically usually only applied to the octave bassoon. One of the most common terms used to describe these instruments is the term tenoroon which is a contraction of "tenor bassoon", which is the more correct title of the instrument although tenoroon is quite accepted nowadays. After an absence of about one hundred years, the tenor bassoon made its comeback in 1989 when Guntram Wolf of Kronach made the first modern, Heckel system tenor bassoon. Since that reintroduction the tenor bassoon has flourished, being used as a children's instrument in Germany (and in locales all over the world) and is being looked at by professionals as a serious instrument worthy of use.
Taken from https://en.wikipedia.org/wiki/Tenoroon