I bought my first electric bass in 1966, and have been playing Rock & Roll professionally, both full time and (lately) part-time, ever since.
Leo Fender invented the first electric bass and sold his first ones in 1950. The tuning is identical to a Bass Viol, the stand-up "Giant Violin" that orchestras have used for over 200 years. The original
Fender Precision Bass, still sold today, was called an electric bass. Electric guitars were invented in the '40's, and the tuning interval of a six-string Spanish guitar (which is what six-string guitars are officially" called) is the same as a bass on the 4 lower pitched strings, 3-6, but an octave higher.
In common parlance, an electric bass has come to be called a bass guitar probably because it looks much more like an elecric guitar than an acoustic bass viol. If a musician asks me what I play, the response is, simply, "bass". If a lay person asks me, I automatically say "bass guitar" just so they'll know what I'm talking about.
I just visited Mars Music's website, and electric basses were, indeed, listed under "Bass Guitars". But when you get to an individual istrument, it is simply calle a "bass". In these more modern times, the term "electric" has become understood.
Hope this clears things up.
Neal