Category:Greek verbs conjugating like 'τραγουδάω-τραγουδώ'

Subcategory with double forms of passive perfect participle ending in -ισμένος (as though from an -ίζω verb)
and less frequent the expected ending -ημένος:

ακουμπάω (akoumpáo)/ακουμπώ as from the rare ακουμπίζω (akoumpízo)

αρχινάω (archináo)/αρχινώ (active only), with parallel αρχινίζω (archinízo)

κοπανάω (kopanáo)/(rare κοπανώ)

τραγουδάω (tragoudáo)/τραγουδώ