"power jam" meaning in English

{
  "forms": [
    {
      "form": "power jams",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "power jam (plural power jams)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Roller derby",
          "orig": "en:Roller derby",
          "parents": [
            "Sports",
            "Human activity",
            "Human behaviour",
            "Human",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "2012 February 19, Rachel Scott, Santa Cruz Sentinel",
          "text": "\"Emma S. Enforcer's power jam also gave her the opportunity to claim nine more points for Black.\"",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A period during which only one jammer is on the track."
      ],
      "id": "en-power_jam-en-noun-HtkRdisC",
      "links": [
        [
          "roller derby",
          "roller derby"
        ],
        [
          "jammer",
          "jammer"
        ]
      ],
      "qualifier": "roller derby",
      "raw_glosses": [
        "(roller derby) A period during which only one jammer is on the track."
      ]
    }
  ],
  "word": "power jam"
}

{
  "forms": [
    {
      "form": "power jams",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "power jam (plural power jams)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with quotations",
        "en:Roller derby"
      ],
      "examples": [
        {
          "ref": "2012 February 19, Rachel Scott, Santa Cruz Sentinel",
          "text": "\"Emma S. Enforcer's power jam also gave her the opportunity to claim nine more points for Black.\"",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A period during which only one jammer is on the track."
      ],
      "links": [
        [
          "roller derby",
          "roller derby"
        ],
        [
          "jammer",
          "jammer"
        ]
      ],
      "qualifier": "roller derby",
      "raw_glosses": [
        "(roller derby) A period during which only one jammer is on the track."
      ]
    }
  ],
  "word": "power jam"
}