Entry 1 sense Webster, 1913 Hydrargyrum /(hī̇*drär"jĭ*rŭm)/ · Hy·drar·gy·rum · IPA /haɪˈdɹɑː(ɹ)d͡ʒɪɹəm/ 01 n. Quicksilver; mercury. 1. Quicksilver; mercury.(Chem.)