Castrate rhymes with:
administrate, demonstrate, frustrate, illustrate, interestrate, magistrate, orchestrate, substrate, administrate, arbitrate, concentrate, demonstrate, frustrate, illustrate, infiltrate, interestrate, magistrate, nitrate, orchestrate, penetrate, perpetrate, substrate
Castrate sounds like:
cadorette, castrated, castruita, catered, catherwood, catrett, coauthored, cotret, coudert, cuadrado, cudworth, custard, cutthroat