Etymology tree
Proto-Hellenic *-íďďō
Ancient Greek -ῐ́ζω (-ĭ́zō)
Proto-Indo-European *-mos
Proto-Indo-European *-mós
Ancient Greek -μός (-mós)
Ancient Greek -ισμός (-ismós)der.
Latin -ismuslbor.
Portuguese -ismo
Learned borrowing from Latin -ismus, from Ancient Greek -ισμός (-ismós), from -ῐ́ζω (-ĭ́zō) + -μός (-mós).