counterfeit goods; knock-off; imitation product
Refers to fake or replica products made to look like genuine branded items, often sold illegally.
The bag I bought online turned out to be a counterfeit.
Counterfeit goods were seized at customs.
海賊版 is used for pirated copies of media (DVDs, software, books), whereas 模倣品 is for physical counterfeit goods like bags, watches, etc.
模倣 (imitation) + 品 (goods). A straightforward compound with no irregular historical derivation.