Definition of "bootless"

When, in disgrace with fortune and men's eyes, / I all alone beweep my outcast state / And trouble deaf heaven with my bootless cries

1609, William Shakespeare, “Sonnet 29”, in Shake-speares Sonnets. […], London: By G[eorge] Eld for T[homas] T[horpe] and are to be sold by William Aspley

The lieutenant tried the handle again, but still his efforts were quite bootless. He pushed and kicked, but the door was a strong one.

1844, Sir John William Kaye, Peregrine Pultuney: or, Life in India, page 251