In G.M. Strike, Both Sides See Defining Moment (来源：http://www.EnglishCN.com)

defining moment

关键性时刻; 决定性时刻 (揭示一个人或群体的性格的时刻)

“This really is a defining moment,” said James P. Womack, an expert on manufacturing and co-author of “The Machine That Changed the World,” which studied the plants of Japanese automakers in the United States. “G.M. has backed away from defining moments for generations. And now somebody there has finally said, ‘We have to do this because it’s a new era.’ ”

define

解释,给...下定义
Do you know who defined man as a rational animal?
你知道是谁将人说成是有理智的动物的?
规定,限定,使明确
The powers of the courts are defined by law.
法庭的权力是由法律规定的。
确定...的界线;使...的轮廓分明
The boundary is not clearly defined.
这疆界没有明确划定。
为...的特性,是...的特色[(+as)]
Reason defines man.
理性是人的特点。