Expand is an antonym of compress.
As verbs the difference between expand and compress
is that
expand is to change (something) from a smaller form and/or size to a larger one while
compress is to make smaller; to press or squeeze together, or to make something occupy a smaller space or volume.
As a noun compress is
a multiply folded piece of cloth, a pouch of ice etc, used to apply to a patient's skin, cover the dressing of wounds, and placed with the aid of a bandage to apply pressure on an injury.