Actually slang. Derived from how the conservatives in france, during the French revolutin, sat on the right side of their governing house (whatever that was). In America, (and this is widely misunderstood by college students) Right Wing refers to conservatives who, by their nature, favor a small limited government with little power and little control over the people, with most of the power residing within the local state governments. Basically anti-federalist. In other words, the politicians who DON'T want more government involved with your everyday life. They don't want the government to get too big have a lot of control over the people.
Eisenhower, cosidering his spending and civil rights work, was clearly right wing.