The Bible (e.g., Numbers 34:11, Joshua 12:3) says a body of water called the Kinneret runs along the Promised Land’s eastern border.
The Targumim translate “Kinneret” into Aramaic as “Ginosar”; Josephus (War of the Jews, book III, ch. 10) calls it the Lake of Genezareth (an Anglicization of the Greek version of Ginosar); and the Talmud refers to it as Yam Shel Tiveria or Yamah Shel Tiveria – “The Sea of Tiberias” (e.g., Shabbos 87, Bava Kamma 81, Bechoros 55a, Jerusalem Talmud Shekalim 6:2).
Why does this lake have three different names? And what is its primary name?
The answer to this question has halachic ramifications. A get must include the name of the city in which it is written plus the name of the closest body of water (so that the location is crystal clear). Accordingly, a sofer writing a get in Tiberias must mention the Kinneret. But which name should he use? Rabbi Yosef Karo (1488-1575) and Rabbi Moshe ben Yosef of Trani (1505-1585) hotly debated this question.
According to a popular theory, the pear-shaped Kinneret gets its name from its resemblance to a kinnor (a musical instrument). There is no real source for this assertion, however.
It’s possible that this body of water actually does not have its own name and is identified instead by the most prominent city on its banks. The Bible mentions a fortified city, Kinneret, in the tribal territory of Naftali that was captured in the time of Yehoshua (Joshua 19:35). The name of this city also appears in various ancient inscriptions. Thus, the Bible refers to the nearby body of water as “the Sea of Kinneret” because Kinneret was the most prominent nearby city at the time.
In later times, Kinneret was called Ginosar. The Talmud (Megillah 6a) explicitly states that the Biblical city of Kinneret is the same city as Ginosar. It explains that Ginosar was called Kinneret because “its fruits are as sweet as the voice of a kinnor.” Rabbi Nosson of Rome (1035-1106) defines kinnor as either a type of berry (which Jastrow identifies it as a “thorn jujube” – see also Rashi to Bava Basra 48b) or a musical instrument (“harp” or “lyre”).
The Talmud (Berachos 44a) speaks about the fruits of Ginosar in the most superlative of terms, and the Midrash (Bereishis Rabbah §98:17) exegetically breaks up “Ginosar” into “ganei sarim” (gardens of officers) as the land in Ginosar was especially fertile and valued for its fruits.
Thus, we see that by the Second Temple period, Kinneret had come to be known as Ginosar, but was still a highly prominent city. The nearby body of water therefore came to be known as “the Sea of Ginosar,” and that is the term used for it in works from that era (such as the Targumim and Josephus’ writings).
Another city nearby is Tiberias, so when that city rose in prominence, it became the sea’s namesake. Thus, the Talmud refers to the Kinneret as “the Sea of Tiberias.” By that time, Tiberias had surpassed Kinneret/Ginosar as the most prominent city in the area. Hence also the body of water’s name in Arabic: Buhairet Tabariyya, which means “Sea of Tiberias.”
According to Josephus (Antiquities of the Jews, book XVIII, ch. 8), Herod established the city of Tiberias and named it in honor of the Roman emperor Tiberius (42 BCE-37 CE). The Talmud (Megillah 5b-6a) identifies Tiberias with one of two cities mentioned in the Bible: Chamat or Rakat (Joshua 19:35). The Talmud explains that Chamat (literally, “hot”) refers to the natural hot springs found in Tiberias while Rakat (literally, “empty”) alludes to the fact that even the “empty” (i.e., ignorant) inhabitants of that city were still full of mitzvot like a pomegranate is full of seeds.
The Talmud also offers two explanations for the name Tiberias: 1) the city sits at the tabur (“navel” or “belly button”) of the Land of Israel (in terms of its importance); 2) the name is a portmanteau of “tovah reiyatah” (its sight is good). Tosafos explains that it is aesthetically beautiful with its luscious gardens and orchards.
The Christian Bible commonly calls the Kinneret “the Sea of Galilee,” the name by which the lake is more commonly known to English speakers. Galilee, of course, was the administrative name of the entire northern region of the Holy Land in Hasmonean and Herodian times. So again, the sea was named after its geographical surroundings.