simple past tense and past participle of realize
"She realized she had left her keys in the car when it started raining heavily outside."
In plain English: Realized means when you finally understand something or see what is actually happening.
"I realized I had left my wallet on the table when I went to pay for my coffee."
successfully completed or brought to an end
"his mission accomplished he took a vacation"
"the completed project"
"the joy of a realized ambition overcame him"
Derived from Old French realiser, this term entered English in the late 19th century to mean making something real or bringing it into existence. It originally referred specifically to realizing an idea or plan, later expanding to include becoming aware of a fact through perception.