"Usury" is still a word in use but now, for legal purposes, it means "interest that a lender charges a borrower at a rate above the lawful ceiling on such charges" rather than just any interest at all.
Interest as such is recognized as theft and therefore an injustice.
no, not really, you have to order it chronologically: charging interest was verboten and in law it was called usury. later, interest was deemed ok... but charging too much interest was to be sanctioned and usury was a handy word to use.
Between Christians and Muslims, Christians and Jews, Jews and Muslims different rules may/may-have applied.
Kings (of england, and other places) valued Jews precisely because of the fluidity of their lending to the crown at interest under catholic proscription regarding loans between christians, not the least because at long term consequences in access to jewish loans you could repudiate the debt and (or encourage your citizens to) conduct a pogrom.