tapasi—in severe austerities and penances Madhya 22.42, Madhya 24.219
tapasi—for austerities SB 4.1.17
tapasi—austerity SB 4.23.4
tapasi—in austerities SB 4.24.19
tapasi—in the austerity SB 8.17.18
Can't find any compound Sanskrit words containing tapasi.