What does this English word mean?

Hi, I'm learning English and I don't know what this word mean. "masher", and it's someone in the crowded train or crowded subway train.. What kind of person is this, could you elaborate and explain about the word "masher", and what kind of person it is? Thank you. And, is it a... show more Hi, I'm learning English and I don't know what this word mean. "masher", and it's someone in the crowded train or crowded subway train..

What kind of person is this, could you elaborate and explain about the word "masher", and what kind of person it is? Thank you.

And, is it a common usage? or is it rarely used for this connotation? If there is a better word or expression, could you write them too? Thank you.
Update: OBXMAR and jilllpilll are correct.
A masher is a pervert who touches woman's body. I knew the meaning, because my vocab book says the meaning too, but I asked this question because I wanted to know if this word is really common or not. It looks like this word is not very common. But thanks everyone!
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