...
How like Eve's Apple doth thy beauty grow,
If thy sweet virtue answer not thy show!- Sonnet xciii.
Here Shakespeare names the Apple, the Crab, the Pippin, the Pomewater, the Apple-john, the Codling, the Caraway, the Leathercoat, and the Bitter-Sweeting. Of the Apple generally I need say nothing, except to notice that the name was not originally confined to the fruit now so called, but was a generic name applied to any fruit, as we still speak of the Love-apple, the Pine-apple .... The Anglo-Saxon name for the Blackberry was the Bramble-apple; and Sir John Mandeville, in describing the Cedars of Lebanon, says: "And upon the hills growen Trees of Cedre, that ben fulle hye, and they beren longe Apples, and als grete as a man's heved". In the English Bible it is the same. The Apple is mentioned in a few places, but it is almost certain that it never means the Pyrus malus, but is either the Orange, Citron, or Quince, or is a general name for a tree fruit. So that when Shakespeare and the other old writers speak of Eve's Apple, they do not necessarily assert that the fruit of the temptation was our Apple, but simply that it was some fruit that grew in Eden. ...
Apparently, the word "apple", by the older literary way, was a generic description for 'fruit' (of the orange/citron/quince kinds) - not the 'apple' we know now it as.
To me this underscores the importance of not just etymology, but also:
why we must understand and account for semantic shifts (both of narrowing and broadening); and
why imposing modernist values and literal definitions on older texts can be misleading and dangerous.