means a long, confident step in walking or running — or, figuratively, a notable advance in progress.

from From Old English 'strīdan,' meaning to mount or straddle, and related to Old High German and Middle Dutch words for striding and quarreling. The old sense of 'straddle' lingers in the way a stride spreads the legs wide — the same root that lets you 'bestride' a horse. The modern meaning of forward progress ('great strides') is a later, figurative bloom from the literal long step.