The definition of conceptualize is to form an idea.
An example of conceptualize is for an author to envision the plot for her next novel.
verbcon·cep·tu·al·ized, con·cep·tu·al·iz·ing, con·cep·tu·al·iz·es
To form a concept or concepts of, and especially to interpret in a conceptual way: This cabaret performance was conceptualized as a homage to vaudeville.
To form concepts.