A souvenir is an object that reminds us of a special place or event we've been to. It's usually something we buy or find when we travel.
When people go on vacation, they often like to bring back souvenirs as a memory of their trip. These can be anything from a small keychain or postcard to a beautiful piece of art or local craft. Sometimes, the souvenir itself is also made locally and has some significance, so it's not just a random object. For example, if you visit a famous city like Paris, you might buy a miniature Eiffel Tower as a reminder of your trip.
An item of sentimental value, to remember an event or location.
To take (an article) as a souvenir, especially illicitly, for example during wartime.
