Meaning of GMS in English

GMS /ˌdʒiːem ˈes/ BrE AmE noun [uncountable]

a piece of equipment, like a small computer, that has special software which is able to produce an image of the natural features that exist in a particular area, such as the rocks and the water flowing under the rocks

Longman Dictionary of Contemporary English.      Longman - Словарь современного английского языка.