Armhole

An aposteme gendred in þe purgynge places, þat is to say, of þe brayne vnder þe eres, of þe herte vnder þe arme holes, of þe lyuer in the schares.

Put these ragges and cloutes vnder thine arme holes.

Armhole is a variant on armpit in the west and east Midlands.

He... violently pull'd off her Riding-Hood, and tore it at the Arm Holes in pulling it off.