Panache (French pronunciation: [panaʃ]) is a word of French origin that carries the connotation of flamboyant manner and reckless courage.
The literal translation is a plume, such as is worn on a hat or a helmet, but the reference is to King Henry IV of France (13 December 1553 – 14 May 1610). Pleasure-loving and cynical military leader and the best-loved of the kings of France, he was famed for wearing a striking white plume in his helmet and for his war cry: "Follow my white plume!" (French: "Ralliez-vous à mon panache blanc!").
Cyrano de Bergerac
The epitome of panache and the reason for its establishment as a virtue are found in Rostand's depiction of Cyrano de Bergerac, in his play of that name. (Prior to Rostand, panache was not necessarily a good thing and was seen by some as a suspect quality).
Panache is referred to explicitly at two points in the play but is implicit throughout: for example, Cyrano's challenges to Montfleury, Valvert, and at one point, the whole audience, at the theatre (Act I) and his nonchalant surrender of a month's salary to pay for the damages; his duel with a hundred footpads at the Porte de Nesle (Act II), and his dismissal of the exploit when talking to Roxane ("I've been much braver since then"); his crossing the Spanish lines daily to deliver Roxane's letters (Act IV); and his leaving his deathbed to keep his appointment with her in Act V.
The explicit references bring in the double meaning: first, in Act IV, when sparring with De Guiche over the loss of his (de Guiche) white sash, he says, "I hardly think King Henry would have doffed his white panache in any danger." Also, Cyrano's last words were "yet there is something still that will always be mine, and when I go to God's presence, there I will doff it and sweep the heavenly pavement with a gesture: something I'll take unstained out of this world... my panache."
- The dictionary definition of panache at Wiktionary