PRECARIOUS, literally, held on the good-will of another, or on entreaty (Lat. prex, precis, prayer) to another. The word is used, in law, of a tenure of land, office, etc., held at the pleasure of another. In general usage it has the significance of something uncertain, dangerous or risky.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)