"Mach band" meaning in English

{
  "etymology_text": "Named after the physicist Ernst Mach.",
  "forms": [
    {
      "form": "Mach bands",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "Mach band (plural Mach bands)",
      "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": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Optical illusions",
          "orig": "en:Optical illusions",
          "parents": [
            "Vision",
            "Senses",
            "Perception",
            "Body",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "Any of a series of bands of slightly different shades of grey that make up an optical illusion where the contrast between the bands appears to be exaggerated as soon as they contact one another."
      ],
      "id": "en-Mach_band-en-noun-kSntkDG2",
      "links": [
        [
          "optical illusion",
          "optical illusion"
        ],
        [
          "contrast",
          "contrast"
        ],
        [
          "exaggerate",
          "exaggerate"
        ]
      ],
      "wikipedia": [
        "Ernst Mach",
        "Mach bands"
      ]
    }
  ],
  "word": "Mach band"
}

{
  "etymology_text": "Named after the physicist Ernst Mach.",
  "forms": [
    {
      "form": "Mach bands",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "Mach band (plural Mach bands)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English eponyms",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Optical illusions"
      ],
      "glosses": [
        "Any of a series of bands of slightly different shades of grey that make up an optical illusion where the contrast between the bands appears to be exaggerated as soon as they contact one another."
      ],
      "links": [
        [
          "optical illusion",
          "optical illusion"
        ],
        [
          "contrast",
          "contrast"
        ],
        [
          "exaggerate",
          "exaggerate"
        ]
      ],
      "wikipedia": [
        "Ernst Mach",
        "Mach bands"
      ]
    }
  ],
  "word": "Mach band"
}