It's certainly teasel if it has a row of thorns along the underside spine of the leaf.
It's a dynamic accumulator, with a deep tap root. It pierces clay soils and brings up important micronutrients. The leaves are good for mulching. It collects water at the base of its leaves. It will mature with a distinctive spiky seed pod that crafters work into arrangements when dried. Goats love it.
As with most weeds, it's trying to tell you something. If it's not right where you want something else, I'd let it grow until before it goes to seed, then cut it down and spread the leaves out on your fall/winter beds for mulch. As a mulch, it will reduce erosion while putting into surface soil minerals and micro-nutrients that it probably lacks.
Either that, or feed it to someone's goat! As weeds go, it's a pretty nice one. :-)