In response to cxt's concerns about definitions, I do recognize that translations of words, across different languages, can be a challenge, especially when going from Asian to Western languages.
I would also agree with cxt's point that the term combat is open to interpretation and is not necessarily associated with warfare.
However, the common Chinese/Japanese character used for "martial" does have a fairly strong link to warfare.
The Japanese character bu (Chinese - wu) is widely translated as martial. The character has two radicals, one whose meaning has been constant, and one whose meaning has changed over time. The first radical (which has changed) is currently defined as "to stop". This character also appears to have once been defined as "foot". There is some discussion on the web on the interpretation of the term foot. It could be for stopping, but it is also likely that it would be interpreted as "advancing".
The second radical in bu/wu is "spear". No real ambiguity there.
So the current reading for bu (martial) is "to stop a spear" and the older reading may have been more associated with "advancing spear".
Interestingly, as the use of martial arts have lost effectiveness on the battlefield, there also has been a shift from the offensive systems required for warfare (advancing spear), to the more defensive systems common in empty hand fighting today (to stop a spear).
If any Chinese scholar knew the timeframe that the radical "foot" evolved to the radical "to stop" I would be grateful if they would share it.