aha moment

noun Informal.

a point in time, event, or experience when one has a sudden insight or realization: My aha moment was when I put on my shorts from last summer and they didn’t fit.

Origin of aha moment

from the expression aha, used to signal sudden awareness or comprehension

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for aha moment

aha moment

noun

an instant at which the solution to a problem becomes clear

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012