Thrombo is defined as blood clot.
An example of thrombo used as a prefix is in the word thrombosis, which means the formation of a blood clot.
thrombus, blood clot: thrombocyte
Origin of thrombo-; from Classical Greek thrombos, a clot: see thrombus
Blood clot; blood clotting: thromboplastic.
Origin of thrombo-Greek, from thrombos, clot.