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Pronunciation varies by accent · noun
(historical) The name originally proposed for element 72, now called hafnium; the discoverer, Georges Urbain, conjectured it to be a rare earth element, and proposed the symbol Ct; but subsequent work showed it to be a transition element, and hafnium was given the symbol Hf..
Use celtium when its meaning, tone and grammar fit the full sentence. A synonym is not always a direct replacement.
Celtium means (historical) The name originally proposed for element 72, now called hafnium; the discoverer, Georges Urbain, conjectured it to be a rare earth element, and proposed the symbol Ct; but subsequent work showed it to be a transition element, and hafnium was given the symbol Hf..
The closest synonym depends on the sentence and intended sense.
The opposite depends on the specific sense.
Use celtium where its definition matches the intended context.
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