Yovel and Shofar
When you try to find a meaning of a word, some times the meaning can not be found in a dictionary, but in a book of a different nature. I was reading a book about justice in the ancient world and stumbled upon a good interpretation of the word יובל YoVeL- Jubilee. Usually the word is explained as connected to the word Yuvlah in Aramaic which is a ram, or to be more precise, a ram's horn used to sound a blast on Yom Hakippurim to call freedom to the land (Lev 25:9). We also find in Akkadian the word yabilu with the same meaning. In a different context we find that the word was used in the ancient near east also as a symbol of freedom, but in a different way. Another word that uses the same root is Yuval which is a stream of water (Ramban on the verse). In Akkadian the word is yabilitu(m)-water conduit (notice that the words yabilu/yabilitu are basically the same but one is suffixed creating a different word). The idea is that a free person is like a stream that can flow freely without being stopped. Freedom was seen as not stopping a person from being who they are and what they want to do.
What ever the original meaning might be, both are connected to the biblical practice (maybe to mean both), but I personally prefer the second because it touches on the actual meaning of what is being done (freedom), and not the sign that was used (Shofar).