Deuto- \Deu"to-\or Deut- \Deut-\ (d[=u]t-)[Contr. from Gr. ? second.]

(Chem.) A prefix which formerly properly indicated the second in a regular series of compound in the series, and not to its composition, but which is now generally employed in the same sense as bi-or di-, although little used.

Source: Webster's Revised Unabridged Dictionary (1913)