This is the 6690th most frequent Polish word.
dzianinowe
"Dzianinowe" means "knitted" or "knitwear" in English.
Here, "dzianinowe" functions as an adjective describing the type of sweaters, emphasizing their material composition, which is knit-fabric.
Te dzianinowe swetry są bardzo wygodne.
These knit sweaters are very comfortable.
In this case, "dzianinowa" is an adjective modifying "czapka" (hat), specifying that the hat is made of knit material.
Podoba mi się ta dzianinowa czapka, którą masz.
I like that knit hat you have.
Here, "dzianinowe" qualifies "legginsy" (leggings), indicating that they are made of knit fabric, relevant to the context of athletic wear.