A subchromat is a person who is partially or fully colour-blind. To a non-drafter, this is of far less significance, but to a drafter it is a source of embarrassment, since their whole lives revolve around colours. However, it does not necessarily preclude one's drafting ability. Any colours that he/she can see will still be draftable, often with the same amount of success that the drafter would have otherwise. A green-red subchromat may still be a powerful blue drafter or even a bichrome or polychrome in the colours that he/she can see.
Very few women are subchromats, the one known instance being Teia. Far more men are subchromatic.