Synonyms of unflappability

2 Syllables
coolness, aplomb, poise, sang-froid
3 Syllables
self-control, steadfastness
4 Syllables
cool-headedness, coolheadedness, nonchalance, self-possession, composure, stability, collectedness
5 Syllables
level-headedness, equanimity
6 Syllables
imperturbableness
7 Syllables
imperturbability