(SM) Maybe not an "American Indian" summer but certainly an American "Indian summer" as it seems the phrase is well-established in the US where, according to Wikipaedia, it has the rather precise meaning of an unseasonably warm spell that takes place after the first ground frost of autumn. But it's possible they got it from the Raj, via us.

[Rosie] In our (italophone) house we just use whichever verb comes to mind and conjugate it appropriately (laziness on my part which my wife has caught). This leads to some hilarity but mainly exasperation of the shit-we-must-cure-ourselves-before-kids-come-along variety.

Rereading that it's not as clear as I had hoped. I mean if I can't be bothered to trawl my mind for the Italian verb I just stick the English one in and slap -are on the end.

[Rosie] "Laxity" is a pretty mild word for you to use in this context, Rosie; most unlike you. :-) I thought you devastated much more about this kind of thing.

I'd always assumed Indian summer was a U.S. phrase, simply because I don't ever remember hearing it before I moved to the U.S. (many summers, Indian and not, have passed since then).

On the other hand, Rosie, I'm not sure you should trust your chosen source too much.