Early 17th century; earliest use found in John Selden (1584–1654), lawyer and historical and linguistic scholar. From Mohammed, variant of Muhammad + -ism.
Definition of Mohammedism in US English:
Mohammedism
nounmʊˈhamədɪz(ə)m
The religion founded by Muhammad; Islam.
Origin
Early 17th century; earliest use found in John Selden (1584–1654), lawyer and historical and linguistic scholar. From Mohammed, variant of Muhammad + -ism.