/ ˌlɒk nes ˈmɒnstə(r); ˌlɒx; NAmE ˌlɑːk nes ˈmɑːnstər; ˌlɑːx/ (also informal Nes·sie ) noun
a large creature that some people think lives underwater in Loch Ness, a lake in Scotland, and looks like a dinosaur (= an animal that lived millions of years ago) . Many people claim to have seen it but scientists have never found any evidence that it really exists.