What does "precarious" mean?

Precarious: Held by a doubtful tenure; depending on unknown causes or events; exposed to constant risk; not to be depended on for certainty or stability; uncertain; as, a precarious state of health; precarious fortunes. "Intervals of partial and precarious liberty." Macaulay. -- Precarious, Uncertain. Precarious in stronger than uncertain. Derived originally from the Latin precari, it first signified "granted to entreaty," and, hence, "wholly dependent on the will of another." Thus it came to express the highest species of uncertainty, and is applied to such things as depend wholly on future casualties. -- Pre*ca"ri*ous*ly, adv. -- Pre*ca"ri*ous*ness, n.