^Sure, it's a military with somewhat redefined functions, but I don't think it makes sense to say it's only partly or occasionally a military. It's got ranks and hierarchy and uniforms and stuff. An officer remains an officer whether fighting Romulans or cataloguing alien moss samples.
Maybe a more inclusive term for it would be "uniformed service." In the US, the uniformed services are counted as the Army, Navy, Air Force, Marines, Coast Guard, Public Health Service Commissioned Corps (led by the Surgeon General), and the NOAA Corps, a scientific agency within the Commerce department. I guess you could say that Starfleet is usually pretty much a cross between those last three, with elements of the Navy/Air Force as well.
Maybe a more inclusive term for it would be "uniformed service." In the US, the uniformed services are counted as the Army, Navy, Air Force, Marines, Coast Guard, Public Health Service Commissioned Corps (led by the Surgeon General), and the NOAA Corps, a scientific agency within the Commerce department. I guess you could say that Starfleet is usually pretty much a cross between those last three, with elements of the Navy/Air Force as well.