It is indeed “International Atomic Time” in English, for what it’s worth I chose to use the French version of the acronym because using the English text requires more explanation why the acronym for “International Atomic Time” is not IAT but TAI, than just using the French name which matches the acronym and letting the curious google some more about the topic.

Also for bonus points the curious should read about UTC and how no one is precisely sure why that’s the version we got, spoilers: The English acronym and the French acronym both aren’t in the correct order for us to use the letters UTC, yet the acronym is UTC and no one is sure exactly why, like it may have been a compromise hashed out over drinks at some hotel bar between metrologists at a conference and written into the text that way without comment… it’s lost to history (at least the history I’ve been able to find when I ran down this rabbit hole)