fruityoudaoicibaDictYouDict[fruit 词源字典]
fruit: [12] English acquired fruit via Old French fruit from Latin frūctus, a source more clearly on display in fructify [14], fructose [19], etc. The underlying meaning of the Latin noun seems to have been ‘enjoyment of that which is produced’, for it came, like frūx (source of English frugal), from a base which also produced the verb fruī ‘enjoy’.

By classical times, however, it had passed from ‘enjoyment’ to the ‘product’ itself – the ‘rewards’ of an enterprise, the ‘return’ on an investment, or the ‘produce’ obtained from the soil or from farm animals. When it reached English this latter meaning had narrowed down somewhat, but it was still capable of being used far more broadly, for any ‘edible vegetable’, than we would do today, except in certain archaic expressions such as ‘fruits of the earth’.

The modern restriction to the edible reproductive body of a tree, bush, etc dates from the 13th century. English retains, of course, the more general sense ‘product, result’, although this is now usually expressed by the plural fruits.
=> fructify, frugal[fruit etymology, fruit origin, 英语词源]
exercise (n.)youdaoicibaDictYouDict
mid-14c., "condition of being in active operation; practice for the sake of training," from Old French exercice (13c.) "exercise, execution of power; physical or spiritual exercise," from Latin exercitium "training, exercise" (of soldiers, horsemen, etc.); "play;" in Medieval Latin also of arts, from exercitare, frequentative of exercere "keep busy, keep at work, oversee, engage busily; train, exercise; practice, follow; carry into effect; disturb, disquiet," literally "remove restraint," from ex- "off" (see ex-) + arcere "keep away, prevent, enclose," from PIE *ark- "to hold, contain, guard" (see arcane).

Original sense may have been driving farm animals to the field to plow. Meaning "physical activity for fitness, etc." first recorded in English late 14c. Also from late 14c. as "a carrying out of an action; a doing or practicing; a disciplinary task." In reference to written schoolwork from early 17c. The ending was abstracted for formations such as dancercise (1967); jazzercise (1977); and boxercise (1985).