This is the 2119th most frequent Polish word.
oparciu
The Polish word "oparciu" means "support" or "backrest" (dative or locative case of "oparcie").
In this sentence, "oparciu" refers to the backrest of the couch, emphasizing the physical support it provides.
Siedziałem w oparciu o kanapę.
I was sitting against the backrest of the couch.
Here, "oparciu" is used figuratively to indicate the basis or foundation using the expression "w oparciu o," which means "based on."
Opracowaliśmy projekt w oparciu o najnowsze dane.
We have developed the project based on the latest data.
This usage shows "oparciu" in a formal context, referring to making a decision with reliance or consideration of rules.