They didn’t have a word for sphere back then. A sphere is simply a 3D circle.
a sphere does not have an edge... you can travel indefinitely around a sphere and never reach a boundary or edge. On the other hand, if the earth is flat, it must have an edge somewhere, unless the earth is an infinite plane.
... the Bible does not teach that the earth is flat. It was Bible skeptics who introduced this false claim in the 19th century. It is a shame that professed Bible-believers recently have embraced this false argument and have gone on to promote the flat earth. When combined with its many scientific and observational problems, the flat-earth theory is disproven.