I literally just pulled the first definition. It is not my dictionary, but Google's. If you don't like the first definition that comes up, that is on you, not me.
Second, it is not even clear that any US citizens will be shipped off. Bukele is just offering it and Trump said he isn't sure if it will happen.
Third, US citizens are able to serve their sentence in a foreign country if they so choose since 1977 [1]. Obviously this situation is not the same, but the US does send its citizens to foreign prisons sometimes.
Tell me, when in history has the US sent its citizens to overseas prisons?