The length of time you hold an investment before you sell it is called

As long as you keep money in stocks or maybe banks without withdrawing it out it's called equity

The answer is: Time horizon

For each investors, the amount of time horizon would be different depending on the investors's speculation and expectation.

For example, if the investors expect that their investment would radically increase in value in the future, the time horizon for them would usually be high since they would not sell their investments until their expectations are fulfilled.