Origin: Greek prefix poly-
Polyethylene has 2 different meanings across 1 category:
a lightweight thermoplastic; used especially in packaging and insulation
"The warehouse manager swapped out the heavy glass jars for bottles made from polyethylene to reduce shipping costs and improve safety during transit."
A polymer consisting of many ethylene monomers bonded together; used for kitchenware, containers etc.
"The reusable food storage container is made from durable polyethylene that won't crack when frozen or microwaved."