"uA" meaning in English

{
  "etymology_text": "Derived from the similarity between the letter u and the Greek letter µ.",
  "head_templates": [
    {
      "args": {
        "1": "en",
        "2": "symbol"
      },
      "expansion": "uA",
      "name": "head"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "symbol",
  "senses": [
    {
      "alt_of": [
        {
          "word": "µA"
        }
      ],
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English entries with language name categories using raw markup",
          "parents": [
            "Entries with language name categories using raw markup",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English symbols",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "topical",
          "name": "Symbols for SI units",
          "parents": [
            "SI units",
            "Units of measure",
            "Metrology",
            "Quantity",
            "Applied sciences",
            "Mathematics",
            "Sciences",
            "Formal sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "Alternative spelling of µA"
      ],
      "id": "en-uA-en-symbol-8V7pimMi",
      "links": [
        [
          "µA",
          "µA#English"
        ]
      ],
      "tags": [
        "alt-of",
        "alternative"
      ]
    }
  ],
  "word": "uA"
}

{
  "etymology_text": "Derived from the similarity between the letter u and the Greek letter µ.",
  "head_templates": [
    {
      "args": {
        "1": "en",
        "2": "symbol"
      },
      "expansion": "uA",
      "name": "head"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "symbol",
  "senses": [
    {
      "alt_of": [
        {
          "word": "µA"
        }
      ],
      "categories": [
        "English entries with incorrect language header",
        "English entries with language name categories using raw markup",
        "English lemmas",
        "English symbols",
        "English two-letter words",
        "Symbols for SI units"
      ],
      "glosses": [
        "Alternative spelling of µA"
      ],
      "links": [
        [
          "µA",
          "µA#English"
        ]
      ],
      "tags": [
        "alt-of",
        "alternative"
      ]
    }
  ],
  "word": "uA"
}