arm to arm

Hello,

Is there any specific language term for phrases like that:

arm to arm
hand in hand
face to face
wall-to-wall
mother and child
town and country
church and state

given the fact that these are deprived of any articles?

Ellipsis, collocations...?

Thank you, Ewelina

They are collocations, and in some cases there could be ellipsiis too, but I don't know of a special term.