Definition from Wiktionary, the free dictionary
- A kind of coarse twilled cotton or cotton and linen stuff.
- A class of cloth including corduroy and velveteen.
- Pompous, inflated or pretentious writing or speech.
- Claudius […] has run his description into the most wretched fustian.
pompous, inflated or pretentious writing or speech
- 1882, Fustian, of which I have found only one entry before 1401, occurs frequently in the fifteenth and sixteenth centuries. It appears to have been a ribbed cloth. — James Edwin Thorold Rogers, A History of Agriculture and Prices in England, Volume 4, p. 568.
Usage notes 
- Used in the sense of "pompous" since at least the time of Shakespeare. For this shift of meaning, compare bombast.