It's hardly a useless word. In fact, it becomes essential when a couple or more poets gather and discuss a pantoum written or read by any of those present. I, myself, have written a pantoum or two, and have discussed the pantoums written by my peers and predecessors.

Victor Hugo and Charles Baudelaire found the form interesting enough to produce enough pantoums to start a trend in the nineteenth century.

In recent years, poets Carolyn Kizer and John Ashbery have produced, respectively, "Parent's Pantoum" and "Pantoum".

Perhaps pantoum is an obscure term of art, but in its own little corner of the world, it remains an essential word which performs the function of naming a lively and useful form.

Namaste.