English

Noun

defining moment ‎(plural defining moments)

1. A moment in time that defines something, such as a person's success or failure, achievement or demise, talent, etc.
2. A point at which the essential nature or character of a person, group, etc., is revealed or identified.

References

• Random House Kernerman Webster's College Dictionary

See also

• critical mass
• killer app
• make-or-break