Learner's definition of OVERWHELM
to affect (someone) very strongly
to cause (someone) to have too many things to deal with
The many requests for assistance overwhelmed them. = They were overwhelmed by the many requests for assistance. [=they could not respond to the many requests for assistance because there were too many]
Don't overwhelm him with facts.
They were overwhelmed with work.
to defeat (someone or something) completely
to cover over (something) completely with water