Long-term investments definition including break down of areas in the definition. Analyzing the definition of key term often provides more insight about concepts. Long-term investments can be defined as: Long-term assets not used in operating activities such as notes receivable and investment in stock and bonds. Long-term investments refer to what many of us think of when we talk about investments, investments like stock and bonds. The term investment can be confusing because investment can mean different things in different contacts. For example, all assets are an investment in some way because the reason the company has assets is for those asset to help generate revenue in the future, the company investing in asset in order to receive a return. Long-term investment is a narrower definition of investment.