Presidential hopeful Bernie Sanders is clarifying where he stands on socialism, specifically democratic socialism, arguing it has historical roots in the U.S.

"What Roosevelt was stating, in 1944, what Martin Luther King Jr. stated in similar terms 20 years later, and what I believe today is that true freedom does not occur without economic security," Sanders said Thursday at Georgetown University.

"Socialism" isn't wildly popular in the U.S. Less than half of responders to a Gallup poll this summer said they'd vote for a socialist president.

The word can mean a lot of different things in different contexts, however.

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"We're gonna win because first we're gonna explain what democratic socialism is," Sanders said during the CNN Democratic debate.

Even democratic socialism, the label Sanders has used, is broad and has been used to describe everything from comprehensive childcare in Scandinavian countries to Social Security in the U.S. (Video via Aarhus University)

"My view of democratic socialism builds on the success of many other countries around the world," Sanders said during Thursday's speech.

Sanders could use a boost. In the past month, his poll numbers have fallen in both New Hampshire and Iowa. (Video via Bernie Sanders for President)

This video includes images from Getty Images, the Library of Congress and Andra MIhali / CC BY SA 2.0.