boot sandals; sandal boots
Hybrid footwear combining features of boots and sandals; often open-toed or with cutouts, but with a boot-like shaft or coverage.
Wearing boot sandals in summer is stylish and cool.
That brand's boot sandals are reputed to be comfortable.
Wasei-eigo or direct loan from English 'boot sandals' / 'sandal boots', referring to hybrid footwear.