monoethyl
/ˌmɒnə(ʊ)ˈiːθ(ɪ)l/ /ˌmɒnə(ʊ)ˈɛθ(ɪ)l/(also monethyl) Chemistry
adjective
Attributive Containing one ethyl group.
Origin
Late 19th century; earliest use found in Henry Roscoe (1833–1915), chemist and university administrator. From mono- + ethyl.