monohydrogen
/ˌmɒnə(ʊ)ˈhʌɪdrədʒ(ə)n/Chemistry
adjective
Attributive Designating compounds containing one hydrogen atom or ion for each combining radical or ion.
Origin
Late 19th century; earliest use found in Henry Roscoe (1833–1915), chemist and university administrator. From mono- + hydrogen.