אוקימתא (from להקים - to put up) is putting a statement in a specific more elaborate way.
In short, when there are two (or more) contradicting sources that bring seemingly opposite opinions, Ukimta is used to limit each statement's application to a specific, non-overlapping situation that eliminates the contradiction. For example, Brochos 45b:
תני חדא ...
An okimta (not okinta) is used generally to advocacy a sentence, generally a Mishna or a Berayita, which seems false or superfluous.
From the Darke Hatalmud from Rabbi Yitschak Kampenton paragraph 4
There are two kinds of Okimta, the first is to reduce the scope of the sentence (contextualization), despite that it seems to be a general sentence to a ...
Rav Hirsch says that calling by name is this case expresses the setting up of the mission and purpose of the item which is called by the names involved.
In any case, where Hashem dowes call something by a name it always
expresses a mission, a calling for the one to be so called, as Abraham,
Israel etc. It is accordingly here also to be taken in the ...