Yeah, it was a poor choice of nomenclature, since, in common, nontechnical parlance, "probable" and "likely" are very close semantically. Though I'm not sure which came first, the choice of "likelihood" for the mathematical concept or the casual use of "likely" as more or less synonymous with probable.
My guess was always that "probability" came first, and they needed a different word for "likelihood" when the latter concept became formalized.