E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
literally means the produce of the bombyx (Middle Latin bombax, Greek bombux), and applied to cotton-wool used for padding. The head of the cotton plant was called bombast or bombace in the sixteenth century. Bombast was much used in the reign of Henry VIII. for padding, and hence inflated language was so called.