In Karate and other Japanese styles you often see the term "ka" at the end of a martial art to signify a
The problem that I have is when I see Hapkido-ka, Taekwondo-ka etc as here they are mixing terminology from the Japanese Martial Arts with terminology from Korean Martial Arts. If you are going to use foreign terms in your martial arts study you should stick with established terms from your martial art. The correct term for Taekwondo student, practisioner or person in Korean is not "-ka" it is "-in". Taekwondo-in, hapkido-in, gumdo-in, etc. Sometimes I see this ridiculed in online forums but it is correct usage of Korean language and I find it very odd that the Japanese ending -ka is tolerated but the Korean ending -in is not.
Actually I will ramp this upa notch: If you are going to use foreign terms for your "foreign martial arts" study or instruction, strive to keep the terminology the same Language as the native land of the martial arts you are studying and or teaching. If you study or teach Taekowondo use Korean terms. Insted of Bunkai, use Boonhae. Instead of Hikite use Dangkinun son. Instead of using Oyo use Eungyoung. Instead of using Hojo Undo, use Buchu Undong. The list goes on. If you have any troubles just swollow your pride and ask. It is really that simple, and especially today when you have twitter, facebook and other social media where there are so many people to ask.