Learner's definition of SOAPBOX
: a box or small platform that someone stands on to give a speech to people in an outdoor, public place — often used figuratively to describe making speeches or expressing strong opinions
His fame as an actor provides him with a soapbox to encourage young people to vote.
He jumped on the soapbox and spoke out against the war.
She needs to get off her soapbox and stop telling people what to do.