[1805–15; ‹ L, equiv. to impluv-, base of impluere to rain (upon, into) (im- im-1 + pluere to rain; cf. pluvial) + -ium -ium]This word is first recorded in the period 1805–15. Other words that entered Englishat around the same time include: alpaca, backlash, diminishing returns, makeup, platinum-ium is a suffix found on nouns borrowed from Latin, esp. derivatives of verbs (odium; tedium; colloquium; delirium), deverbal compounds with the initial element denoting the object of the verb (nasturtium), other types of compounds (equilibrium; millennium), and derivatives of personal nouns, often denoting the associated status or office(collegium; consortium; magisterium); -ium also occurs in scientific coinages on a Latin model, as in names of metallic elements(barium; titanium) and as a Latinization of Greek -ion (pericardium)