Is boarding a cab correct English?

"Boarding a cab" is not the most common or natural way to say that in English.

Here's why:

* "Boarding" usually implies getting on a larger vehicle like a plane, train, or boat.

* "Getting into" or "getting in" a cab is the more common phrase.

Here are some correct ways to say it:

* "I'm getting into a cab."

* "He got in the cab and drove off."

* "We're getting into a taxi."

"Boarding" could be used in a very specific context, such as if you're describing the process of getting into a cab specifically for a long journey or a tour, but it's not the standard way to say it.