noun, noun which may take the genitive case particle 'no'
through something; with something in between
Describes an action done with a physical barrier (screen, curtain, door, etc.) between people. Often used adverbially as 物越しに.
See also: 越し (ごし)
カーテン物越しに話す。
Talk through a curtain.
物越しに相手の気配を感じた。
I sensed the other person's presence through the barrier.
越し is a suffix meaning 'across' or 'through', while 物越し specifically emphasizes a physical object as the barrier.
Compound of 物 (もの, 'thing') + 越し (ごし, 'across, through'). The exact historical derivation is uncertain, but the meaning is transparent from its components.