cashyoudaoicibaDictYouDict[cash 词源字典]
cash: [16] Cash originally meant ‘money-box’. English acquired it via French casse or Italian cassa from Latin capsa ‘box’ (source of English case). It was not until the mid 18th century that this underlying sense died out, leaving the secondary ‘money’ (which had already developed before the word entered English). Cashier ‘person in charge of money’ [16] is a derivative, coming from French caissier or perhaps from Dutch cassier, but the verb cashier ‘dismiss’ [16] is completely unrelated.

It comes from Dutch casseren, a borrowing from Old French casser ‘discharge, annul’. This in turn goes back to Latin quassāre ‘break up’, source of English quash.
=> case[cash etymology, cash origin, 英语词源]
stock (n.2)youdaoicibaDictYouDict
"supply for future use" (early 15c.), "sum of money" (mid-15c.), Middle English developments of stock (n.1), but the ultimate sense connection is uncertain. Perhaps the notion is of the "trunk" from which gains are an outgrowth, or from stock (n.1) in obsolete sense of "money-box" (c. 1400). Meaning "subscribed capital of a corporation" is from 1610s.

In stock "in the possession of a trader" is from 1610s. Meaning "broth made by boiling meat or vegetables" is from 1764. Theatrical use, in reference to a company regularly acting together at a given theater, is attested from 1761. Figurative phrase take stock in "regard as important" is from 1870. As the collective term for the movable property of a farm, it is recorded from 1510s; hence livestock.