1. To surge over and submerge; engulf: waves overwhelming the rocky shoreline. 2. a. To defeat completely and decisively: Our team overwhelmed the visitors by 40 points. b. To affect deeply in mind or emotion: 3. To present with an excessive amount : They overwhelmed us with expensive gifts. 4. To turn over; upset: The small craft was overwhelmed by the enormous waves.
when a person is overwhelmed they are taken over by a situation as it is too much to handle, or too much to bear. In a sentence it would be, The girl became overwhelmed with sadness upon finding out her friend died. OR The girl became overwhelmed with joy when she passed her final exam.