Bootless, a.
Etymology: [From Boot profit.]
Unavailing; unprofitable; useless; without advantage or success. Chaucer. I'll follow him no more with bootless prayers. Shak. -- Boot"less*ly, adv. -- Boot"less*ness, n.
Shades of meaning
Fernald has no entry of its own for bootless; he lists it under vain.
Where he writes about it:
That which is bootless, fruitless, or profitless fails to accomplish any valuable result; that which is abortive, ineffectual, or unavailing fails to accomplish a result that it was, or was supposed to be, adapted to accomplish. — from vain