What Is the Term for Holding an Option until Expiration?

The term for holding an option until its expiration date is "exercising" (if ITM) or "letting it expire worthless" (if OTM). It is often referred to as "holding to maturity" or "expiration."

How Is the Expiration of a Futures Option Different from a Stock Option?
Define “Intrinsic Value” of an Option
Define the Term ‘Optimal Exercise Boundary’ in Options Pricing
Can Slippage Occur When Exercising a European-Style Option?
How Does a “Put” Option Affect the Holding Period of the Underlying Stock?
Why Is It Generally Not Optimal to Exercise an American Call Option Early?
What Is the Difference between Exercising and Selling an Option?
What Does It Mean for an Option to Be “In-the-Money”?