This is the 16703rd most frequent Polish word.
wtórnych
"Wtórnych" means "secondary" in English.
The word 'wtórnych' is used here as an adjective to describe raw materials that are secondary in nature, i.e., obtained after initial use.
W procesie recyklingu przetwarzamy produkty wtórnych surowców.
In the recycling process, we process products of secondary raw materials.
In this sentence, 'wtórnych' qualifies 'complications,' indicating these are secondary or resulting from a prior condition.
Skutki wtórnych powikłań po chorobie mogą być poważne.
The effects of secondary complications after an illness can be severe.
Here, 'wtórnych' describes 'effects,' implying they are not the primary effects but ones occurring as a consequence of initial actions.