Astrologically speaking what is the meaning and origin of luck?

Astrologically speaking, the major factor of luck is planet Jupiter and the sign of Sagittarius, the meaning of both -Jupiter and Sagittarius- being "goin' through", "passing through", "aiming", "escaping", "evolving", "travelling", "seeing", "describing" (dis-criminate), "transmitting", "perpetuating" (viable road, promoting life), "spiraling", "expanding", "bridging", "soothing", "smoothing out", "teaching", "projecting", "foretelling", "being tolerant and generous", "un-climaxing", "allowing" (accepting).

Luck is frail - a frivolous thing. The more you feel associated with the above mentioned qualities, the more lucky you are !

The sign of Pisces and planet Neptune are also related to the origin of luck.