‘Fruit’ is a post-conquest French loanword with the OED dating its earliest usage to 1175. Changes to the language of food and food-dishes is a recognized feature of Norman power, (Bragg, 2003, p.37-38) and to that extent ‘loan’ doesn’t really convey the power of the lexical assault.
Prior to the Norman conquest, the Middle English word ‘aepel’, could be used to refer to any ‘edible product of a plant or tree, consisting of the seed and its envelope, esp. the latter when it is of a juicy pulpy nature’ (OED, ‘fruit’, n., 2). Thus ‘aepel’ could refer to a pear, a lemon, a cucumber, a banana (aepel of paradis) or an acorn (aepel of ok). Other variants of the ME word include ‘aepil’, ‘aepul’, ‘eppel’, ‘eappel’, and ‘apple’, (University of Michigan, ME Dictionary, ‘apple’). All these ME words, in turn, are developments of the early Old English ‘aepl’ that the OED dates to before 1100.
In addition to the umbrella term ‘aepel’, the Anglo-Saxon word ‘wæstm’ could also be used to mean the edible products of a tree, as well as its more common use in describing the tree’s productivity and fecundity in general, (Bosworth and Toller, ‘wæstm’; Bragg, 2003, p.52). These latter senses were taken over by the adjective ‘fruitful’, with the earliest recorded use in 1300 (OED, ‘fruitful’). The OED also records the use of ‘acorn’ to mean fruit generally, derived from Gothic, ‘akran’ which itself derived from Old High German, ‘ackeran’, (OED, ‘acorn’). The earliest A-S recorded use is 1000.
So, users of A-S and ME did not use the word that we now use to refer to an apple in the way we now use it, that is to refer to the edible product of the Malus domestica. At the head of the first philosophical investigation Wittgenstein quotes Augustine’s description of his process of learning language, and in particular the learning of the names of ‘things'. When describing how the shopkeeper uses language to fulfill the order Wittgenstein concentrates upon the understanding of the adjectives (‘red’ and ‘five’). However, the semantic narrowing of ‘apple’ demonstrates ... Well I suppose in Saussurian terms it could be said to be an example of a general arbitrariness in the naming of things, an example of diachronic change. In terms of Wittgenstein I suppose that although the twenty first century shopkeeper would understand the meaning of ‘apple’ in an entirely different way from that of a tenth-century Anglo-Saxon trader it wouldn't really matter as long as the customer happily left the market with their basket of apples, and the trader had made the sale.