A bauble is a gaudy and usually cheap decorative object. In American English, the term is now usually synonymous with a spherical Christmas tree decoration, while in British English it retains its more general meaning.
It is probably a blend of two different words, an Old French baubel, a child's plaything, and an old English babyll, something swinging to and fro. It was applied to a stick with a weight attached, used in weighing, to a child's toy, and especially to the mock symbol of office carried by a court jester, a baton terminating in a figure of Folly with cap and bells, and sometimes having a bladder fastened to the other end. Hence it became a term for any triviality or childish folly.
Although its meaning has become restricted in American English, the word has been used by both British and American writers to mean either a small object extravagantly decorated (such as Dickens's "rich bauble of a casket"), a previously valuable object that has lost its worth (such as the suicidal King Aegeus's crown and scepter in Hawthorne's Tanglewood Tales), or even an abstraction such as immortality.