As noted in the official docs for slugfield: 

    "Slug is a newspaper term. A slug is a short label for something, containing only letters, numbers, underscores or hyphens. They’re generally used in URLs."

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A short label for something, containing only letters, numbers, underscores or hyphens. They’re generally used in URLs. For example, in a typical blog entry URL

    https://website.com/django/learn-about-slug-field

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The "learn-about-slug-field" part is a slug.