Hard to upset

• Cool under pressure

Longman Dictionary of Contemporary English Word definitions in Longman Dictionary of Contemporary English
adjective EXAMPLES FROM OTHER ENTRIES ▪ A good radio-host must be unflappable . EXAMPLES FROM CORPUS ▪ Between numbers by the unflappable Ramblers, the stars are birthing new comedy duets. ▪ But the quiet, efficient and unflappable Brett managed to instil ...

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
1958, from un- (1) "not" + flap (v.) + -able . Originally used in reference to Harold Macmillan, British P.M. 1957-63.

WordNet Word definitions in WordNet
adj. not easily perturbed or excited or upset; marked by extreme calm and composure; "hitherto imperturbable, he now showed signs of alarm"; "an imperturbable self-possession"; "unflappable in a crisis" [syn: imperturbable ]

Wiktionary Word definitions in Wiktionary
a. Remaining composed and level-headed at all times; unswayed by adversity or excitement; impossible to fluster; not becoming frustrated or irritated easily. (1954 to date)

Wikipedia Word definitions in Wikipedia