This term is used to describe 'entirely', 'altogether', 'as a whole' or 'collectively'.
The ぐるみ grammar point is a postfix that indicates entirety or collectively. It is used after a noun to show that the action or state involves everyone or everything in a certain group. It can be translated as 'altogether', 'as a whole', 'groups of', 'all of' or 'entire'. This grammar form is usually used in written language and formal speech.