Spelled many different ways since 1700, it is of both Spanish and French origin. It refers to a framework of sticks that people slept on to be up off the ground, not something that you slap steak onto. That connotation came along in the late nineteenth century, when fish and other food “slept” on a barbecue as they were being cooked. The modern spelling and pronunciation may derive from the French phrase barbe a queue, which means “beard to tail” and has nothing at all to do with the word barbecue.
In the mid 1970s, the Australians shortened the word to barbie, and the movie Crocodile Dundee helped bring the shortened form to America.