A call or put option contract that can be exercised at any time before the expiration of the contract.

An option that can be exercised at any time from inception as opposed to a European Style option which can only be exercised at expiry. Early exercise of American options may be warranted by arbitrage. European Style option contracts can be closed out early, mimicking the early exercise property of American style options in most cases.

an option that can be exercised (i