2.NounA small platform, being or resembling a literal soapbox, on which a person stands in order to give an impromptu speech or espouse his or her views.
"The madman obtained a soapbox which he stood on at the corner of Broadway and Wall street, to shout out his prophecy of the end of the world."
3.NounA platform or outlet, such as a media platform, that a person uses to express his or her opinions.
"The politician used Twitter as his soapbox.; Please stop using council meetings as your own personal soapbox."
4.NounA figurative means of talking repeatedly or at length about one's opinions on one's pet topic.
"He's been on his soapbox all day about the new football coach.; His soapbox is the lack of public toilets in the city."
5.NounThe topic itself.
"His soapbox is the lack of public toilets in the city."
6.NounA soapbox car.
7.VerbTo give a speech from (or as if from) a soapbox.