O que é leading? O que é leading? Having a position in the lead; foremost: the leading candidate. Chief; principal: the leading cause of high inflation. See Synonyms at chief.Of or performing a lead in a theatrical production: a leading role; a leading lady. Formulated so as to elicit a desired response: a leading question. A border or rim of lead, as around a windowpane.Printing The spacing between lines, usually measured in points.