In Arch hold in Scottish Country Dancing the dancers raise their joined hands as high as possible to allow another dancer or a Couple to pass between them, under their arms.
If the dancers making the Arch are stationary, as in Cumberland Reel, they Face each other and Take Both hands; if they are moving towards the dancer(s) who is/are about to go under their Arch, as in Postie's Jig, they Take Nearer hands.
For example, here are some Scottish Country Dances in which the term, Arch Hold, is used in either the Minicrib or the Maxicrib Dance instructions or both -
Isle Of Skye
Rory O' More
Twa Rogueish E'en