Brand names are short, memorable Bitcoin names built around a cultural or numeric anchor rather than a product keyword. Whether one fits depends on the buyer's naming strategy rather than on a category — much like choosing a generic-keyword .com in any other industry.
Brandable names sit apart from the keyword categories. They do not describe a business, they carry one — which means their fit depends entirely on the buyer's naming strategy rather than on search volume.
What makes a Bitcoin brandable work is usually a numeric or cultural anchor the audience already recognises, most often 21. A name a Bitcoiner reads correctly on first sight needs no explanation, and explanation is the most expensive part of launching a brand.