Hmm, maybe we should not look at the word "stetig" in isolation but evaluate the phrase "stetige Reihe".

In German that can be seen as a loan expression from Mathematics (in English: continuous series) and it describes a series of data - and the resulting function y=f(x) thereof - that contains no discontinuities, i.e. the function explicitely excludes "Sprungfunktionen" (

Heaviside step function).

In your OP you said that 3 words is not much of a series - that's true. But strictly speaking, every series of data with more than 1 element is a series which allows us to interpolate or extrapolate other data points, which in turn allows us to evaluate whether the known points are a random collection of points or whether they follow a pattern.

And BTW, a series is not necessarily infinite (unendlich), hence your assumption in the OP is a misconception.

Of course, Mauthner converted "stetige Reihe" from its strictly mathematical definition into a similar definition that can be applied to his "series of 3 translations" (a true mathematical expression of these translations would be impossible, or at least nonsensical, because the value of meaning is subjective, hence mathematically not consistently quantifyable)

Sorry for the outpour of all this boring maths but maybe it helps you making a connection to a suitable Portuguese term