a hypothetical element whose existence was proposed in the 19th century to explain a green line seen in the solar coronal spectrum; this is now known to be highly-ionized iron and nickel
coronium in American English
(kəˈrouniəm)
noun
Astronomy
a hypothetical element once thought to exist because certain spectral lines in the emission spectrum of the solar corona could not be identified by known elements. These lines were subsequently found to be emitted by certain highly ionized metals
Word origin
[1885–90; coron(a) + -ium]This word is first recorded in the period 1885–90. Other words that entered Englishat around the same time include: foregut, retread, roller coaster, seminar, twofer-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)