From here did some take the term "apple" for the forbidden fruit eaten by Adam and Eve? Any suggestions?
The Talmud in Sanhedrin 70b, quotes the various Jewish traditions regarding the identity of the "tree of knowledge good and bad": wheat, vine, fig, and etrog (citron). Probably the answer to the source of the common "rumor" that Eve allegedly ate an apple, is that in ancient Hebrew, the term "Tapu'ach" [also "apple"], is a common term used for something round,[e.g. the round muscle where the tefillin is placed on the upper arm, see R.Y. Karo, Shulchan Aruch, Orach Chaim 27: 1; or the round part of one's heel (Tanhuma Buber, Acharei Mot 3); or the round pile of ashes upon the alter (Mishnah, Tamid 2, 2). Similarly, various cities are named Tapuach, all of which have are located upon a round mountain or hill, e.g. Joshua 12:17; 15, 34 and 53; 17, 7-8. Accordingly, the "tapu'ach" can refer to any round fruit and is a particularly appropriate term for a fruit whose exact identity is unknown or no longer exists. See also Y. Felix, Lexicon Mikra'i, "Tapuach", (ed: M. Solieli, M. Barkoz), Tel Aviv 5755, p. 899, who cites various botanical identifications proposed for "Tapuach", including peach, etrog (citron), and even mandrakes. Similarly, C. Panati, Sacred Origins of Profound Things, N.Y. 1996, suggests that the word apple in English, comes from Old English "aeppel" which means not only the apple but anything round (and especially the center of the eye, today has evolved to be pronounced: "eyeball" hence the phrase: "apple of my eye"). It should also be noted that the "Adam's Apple" bulging from a man's throat is called in Hebrew the "Pikat haGrogeret" (Mishnah, Chulin 10, 4), just like the dry fig is called "grogeret" (Mishna Shabbat, 7, 4), and indeed that is the shape of the bulge. Accordingly, we can understand that the term: "Adam's Apple", probably originated according to the aforementioned tradition that Adam and Eve ate a fig (from where they immediately also took the fig leaves to cover themselves, teaching that "every problem can also be a solution") also known as "apple" as a "generic" name for an unidentified round fruit, as well as his throat bulge. [See also Yalkut Shimoni, Midrash from the 13th century, Kedoshim ch. 615, where a symbolic midrash apparently referring to Adam and Eve, mentions figs, citrons and "tapuchim"]. Rav Ari Shvat (Chwat)