Which investment term refers to an asset that cannot be quickly sold without reducing the price?

The term that specifically refers to an asset that cannot be quickly sold without a significant reduction in its price is "illiquid." Illiquid assets are those that are not easily convertible to cash or that may take a longer time to sell. This lack of liquidity often means that they cannot be sold without an adverse impact on their market value. Common examples of illiquid assets include real estate, collectibles, and certain types of investments, like private equity, which may not have a readily accessible market for quick sales.

In contrast, liquid assets can be sold quickly at stable prices, typically found in markets where there is a high volume of trading, like stocks or bonds. The other terms relate to either the opposite of illiquidity or do not accurately describe the condition of an asset's marketability, reinforcing why "illiquid" is the most appropriate term in this context.