Lockbox is a familiar English word for a small secured container, used for valuables, documents and keys. Paired with BTC, it turns an abstract asset into something one can picture on a shelf or in a vault. The compound is short, easy to spell and works well as a product name printed on packaging. The .com ending gives it the international reach expected of a storage product sold online to customers in many countries.
Alongside the other names of the Wallet & Storage bundle, it gives a custody brand its most physical, hands-on product line. Fitting projects include a physical vault service for sealed seed backups, an online shop for steel plates and small safes, a time-lock savings app that restricts withdrawals by design, or an inheritance service that stores sealed instructions.