We don't have synonyms for thrombi yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are thrombo, thromb and thromb-.
(n) :
(hematology, pathology) A blood clot formed from platelets and other elements that forms in a blood vessel in a living organism, and causes thrombosis or obstruction of the vessel at its point of formation or travel to other areas of the body.
(n) :
(hematology, pathology) A blood clot formed from platelets and other elements that forms in a blood vessel in a living organism, and causes thrombosis or obstruction of the vessel at its point of formation or travel to other areas of the body.