A wallet that can view balances and transactions but cannot spend funds because it lacks private keys.
A watch-only wallet imports public information (addresses, xpubs, or view keys) to monitor balances and activity. It cannot sign transactions because it does not hold the corresponding private keys.
"They track their cold storage using a watch-only wallet on their phone, keeping the spend keys offline on a hardware wallet."
All terms and definitions may update as the Cryptionary improves.