What is the noun of long?

The noun of "long" depends on what aspect of "long" you're referring to:

* Length: This is the most common noun form, referring to the measurement of something from end to end.

* Long time: This refers to a duration, often used in phrases like "a long time ago" or "for a long time."

* Long shot: This refers to a risky attempt or endeavor.

* Long story short: This is an idiom meaning "to summarize" or "to get to the point."

It's important to consider the context to determine the most appropriate noun form of "long."