schistoid,a.Geol.|ˈʃɪstɔɪd| [f. schist1 + -oid.] Having the nature of, or resembling, schist. 1852Th. Ross tr.Humboldt's Trav. II. xxiv. 398 We saw in the mountains of Upper Orinoco,..granites passing into gneiss, and schistoid hornblendes.1858Mayne Expos.Lex.