Wiktionary
n. A container intended to hold smaller containers. vb. (context intransitive English) To pack too much.
Usage examples of "overpack".
An overpacked car with outof-province license plates was stalled on the shoulder, its hood up, its radiator steaming.
He had no real idea what clothes he might need, so he overpacked, as he often did, taking three cases.
The rush hour was in full swing, so they had to wait for two trains before they could find a place in one of the overpacked carriages.
Henry had set his overpacked suitcase down beside the front door and was giving Louise last-minute instructions about forwarding his mail.
Latecomers were still vying for a passage into the already overpacked courtyard and entryway below and a great crowd stood in the streets outside the house, straining to catch the words of the Master.