Cash out is a financial term that refers to the process of converting an investment in a particular asset into cash. The antonyms for cash out include 'invest,' 'buy-in,' and 'trade-in.' Investing refers to putting money into a venture or asset with the expectation of making a profit. Buy-in implies purchasing an asset with the intent to hold on to it, as opposed to liquidating it. Trading-in involves exchanging an old or worn asset for a new one, usually with a top-up of cash or other assets. Other antonyms that relate to cash out include keep, retain, hoard, and save, which all suggest a deliberate decision not to sell or liquidate an asset for cash.