The term 'brain-computer interface' (BCI) is widely used. However, even among experts, its meaning can sometimes be unclear 1-3. Lack of clarity from the term has real-world implications: it can muddle regulatory guidelines, it may confuse investors, it can affect healthcare-coverage policies and could even make it harder for patients to understand opportunities in clinical trials. Here, we propose a taxonomy to align with public understanding of BCI technology and assist regulators, healthcare providers, patients and other stakeholders. Our goal is to initiate the development of a taxonomy for describing BCIs. And we expect it to be refined into precise technical definitions by professional societies and regulatory agencies according to the needs and perspectives of their stakeholders.