Of course it's short for acrobatic. Plenty of native English speakers confuse acrobatic and aerobatic, so it's not surprising that the folks in Japan who laid out the legacy programming stemming from the early 1990s would make that mistake. It's no big deal.

One has to remember that there has been a huge shift in the hobby since then. Helicopters are more aerobatic now than airplanes, but back then? No way, Jose. So many of these little things stick in our hobby. Many of the sometimes confusing contractions in our radio programming have their roots in the tiny displays. It wasn't so long ago that three-letter model naming was considered to be a real selling point, where as now that seems constricting. A very nice radio back then might have had eight model memories or less, with each one assigned just a number. That's why you'll see guys with little pieces of paper taped to their radios sometimes. "1. Cub 2. Extra 3. PT-40" and so on. Pick the wrong model number, and suddenly you've got throws that are reversed and travel that is incorrect. That's why some of the more methodical folks will ensure that their servo horns are all on the same side from model to model. It's also where ideas for nice features such as Model Match come from.