Early 19th century (in an earlier sense). From Arabic muslimīn, oblique case plural of muslimMuslim. In form Moslemen perhaps after Mussulmen, plural of Mussulman.
Definition of Muslimin in US English:
Muslimin
noun
Treated as plural. Muslims collectively.
Origin
Early 19th century (in an earlier sense). From Arabic muslimīn, oblique case plural of muslim Muslim. In form Moslemen perhaps after Mussulmen, plural of Mussulman.