An offshore fund is generally a collective investment scheme domiciled in an offshore jurisdiction. Like the term "offshore company", the term is more descriptive than definitive, and both the words 'offshore' and 'fund' may be construed differently.

The reference to offshore, in the classic case, usually means a traditional offshore jurisdiction such as the Cayman Islands, Jersey or the British Virgin Islands. However, the term is also frequently used to include other corporate domiciles popular for cross border investment structuring, such as Delaware and Luxembourg. In the widest sense, offshore is sometimes used to include any type of cross border collective investment scheme, and popular fund domiciles such as Ireland may be included within the definition of offshore, notwithstanding their substantial size as a country.

Similarly, although the reference to fund can be taken to include any sort of collective investment, within offshore jurisdictions themselves, the term offshore fund is often limited to purely open-ended investment funds (i.e. a fund where the investor can redeem his investment during the life of the fund) where the investment is by way of equity (rather than by debt). This is often because closed-ended investment funds (where the investor cannot redeem out), and funds where the investment is structured by way of debt, are not normally subject to the usual regulatory requirements for investments funds, and so are not treated as funds in the stricter sense of that word.

Although the term is often used as a simply descriptive one, many onshore countries have specific definitions in their legislation or their tax codes for when an investment is treated as an offshore fund. For example, in the United Kingdom see the Offshore Funds (Tax) Regulations 2009, and in the United States see section 871 of the Internal Revenue Code of 1986.