bi-

Deuto- Deu"to-or Deut- Deut- (d[=u]t-)[Contr. from Gr. dey`teros 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. [1913 Webster]