Tauto is defined as the same.
An example of tauto used as a prefix is the word tautologous, meaning repeating the same thing.
the same: tautology
Origin of tauto-Classical Greek ; from tauto ; from to auto, the same
Same; identical: tautomerism.
Origin of tauto-Greek, from tauto, the same, contraction of to auto : to, the; see to- in Indo-European roots + auto, neuter of autos, same, self.