Ottawa's LRT has now been given the name "Confederation Line" for the construction period, and that's what the city, media, and for the most part general public call it. The term "LRT" is now largely deprecated. The odd person will call it the "subway", but nobody even remotely official has ever called it that AFAIK.
The city is still trying to figure out how it wants to deal with the naming issue after construction ends, as the goal is to have the Confederation Line and the existing O-Train be seen as a single transit system, so it needs to come up with a system name as well as some way to give the two lines names with a common theme. The bilingualism issue complicates things as there is no convenient French translation for "LRT"--the literal translation is "train leger", and the city has used that in planning documents, but it sounds really stupid and no francophones ever actually say that. The term "tram" exists in French, but it implies a streetcar-type service, calling Ottawa's subway-like LRT "un tram" would be very weird. In the end, the city is likely to go with the term "metro" simply because of its linguistic convenience.