equanimity
equa.nim.i.ty \.e--kw*-'nim-*t-e-, .ek-w*-\ n [L aequanimitas, fr. aequo animo with even mind] 1: evenness of mind esp. under stress : COMPOSURE 2: right disposition : BALANCE gests a habit of mind that is only rarely disturbed under great strain; COMPOSURE implies the controlling of emotional or mental agitation by an effort of will or as a matter of habit; SANGFROID implies great coolness and steadiness under strain; PHLEGM implies insensitiveness and suggests apathy rather than self-control SYN syn COMPOSURE, SANGFROID, PHLEGM: EQUANIMITY sug
Webster's English Dictionary