I am reading a text as follow:
Wilbur and I went on a cruise for our honeymoon. It was a shame that Wilbur was so seasick, but we had a good time...when he wasn't feeling sick, that is.
What does "that is" at the end of the text mean? I guess it means "I mean", but I am not sure.
You can use the phrases "that is" and "I mean" interchangeably to express more clearly what you have just said. These phrases can also be used before the when-clause as follows:
We had a good time, that is, when he wasn't feeling sick.
Yep! It's used to clarify/put the sentence into context, frequently used in a lighthearted tone.
