"πι" meaning in Greek

{
  "etymology_templates": [
    {
      "args": {
        "1": "el",
        "2": "grc",
        "3": "πεῖ",
        "4": "",
        "5": "pi"
      },
      "expansion": "Ancient Greek πεῖ (peî, “pi”)",
      "name": "uder"
    }
  ],
  "etymology_text": "From the Ancient Greek πεῖ (peî, “pi”).",
  "forms": [
    {
      "form": "pi",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "el",
        "10": "",
        "11": "",
        "12": "",
        "13": "",
        "14": "",
        "15": "",
        "16": "",
        "17": "",
        "18": "",
        "19": "",
        "2": "nouns",
        "20": "",
        "21": "",
        "22": "",
        "23": "",
        "24": "",
        "25": "",
        "26": "",
        "27": "",
        "28": "",
        "3": "indeclinable",
        "4": "",
        "5": "",
        "6": "inv",
        "7": "",
        "8": "",
        "9": "",
        "cat2": "",
        "cat3": "",
        "cat4": "indeclinable nouns",
        "g": "n",
        "g2": "",
        "g3": "",
        "head": "",
        "sort": "",
        "tr2": ""
      },
      "expansion": "πι • (pi) n (indeclinable)",
      "name": "head"
    },
    {
      "args": {
        "1": "n",
        "2": "inv"
      },
      "expansion": "πι • (pi) n (indeclinable)",
      "name": "el-noun"
    }
  ],
  "lang": "Greek",
  "lang_code": "el",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "_dis": "64 36",
          "kind": "topical",
          "langcode": "el",
          "name": "Greek letter names",
          "orig": "el:Greek letter names",
          "parents": [
            "Letter names",
            "Letters, symbols, and punctuation",
            "Names",
            "Orthography",
            "All topics",
            "Proper nouns",
            "Terms by semantic function",
            "Writing",
            "Fundamental",
            "Nouns",
            "Human behaviour",
            "Language",
            "Lemmas",
            "Human",
            "Communication"
          ],
          "source": "w+disamb"
        }
      ],
      "glosses": [
        "Letter pi"
      ],
      "id": "en-πι-el-noun-ho54E~wi",
      "links": [
        [
          "pi",
          "pi"
        ]
      ],
      "tags": [
        "indeclinable"
      ]
    },
    {
      "categories": [
        {
          "_dis": "26 74",
          "kind": "other",
          "name": "Greek entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        },
        {
          "_dis": "13 87",
          "kind": "other",
          "name": "Greek undefined derivations",
          "parents": [
            "Undefined derivations",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        }
      ],
      "glosses": [
        "Used in \"στο πι και φι\" meaning at the drop of a hat."
      ],
      "id": "en-πι-el-noun-zMcA8fni",
      "links": [
        [
          "στο πι και φι",
          "στο πι και φι"
        ],
        [
          "at the drop of a hat",
          "at the drop of a hat"
        ]
      ],
      "tags": [
        "indeclinable"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/pi/"
    }
  ],
  "word": "πι"
}

{
  "categories": [
    "Greek entries with incorrect language header",
    "Greek indeclinable nouns",
    "Greek lemmas",
    "Greek neuter nouns",
    "Greek nouns",
    "Greek terms derived from Ancient Greek",
    "Greek terms with IPA pronunciation",
    "Greek undefined derivations",
    "el:Greek letter names"
  ],
  "etymology_templates": [
    {
      "args": {
        "1": "el",
        "2": "grc",
        "3": "πεῖ",
        "4": "",
        "5": "pi"
      },
      "expansion": "Ancient Greek πεῖ (peî, “pi”)",
      "name": "uder"
    }
  ],
  "etymology_text": "From the Ancient Greek πεῖ (peî, “pi”).",
  "forms": [
    {
      "form": "pi",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "el",
        "10": "",
        "11": "",
        "12": "",
        "13": "",
        "14": "",
        "15": "",
        "16": "",
        "17": "",
        "18": "",
        "19": "",
        "2": "nouns",
        "20": "",
        "21": "",
        "22": "",
        "23": "",
        "24": "",
        "25": "",
        "26": "",
        "27": "",
        "28": "",
        "3": "indeclinable",
        "4": "",
        "5": "",
        "6": "inv",
        "7": "",
        "8": "",
        "9": "",
        "cat2": "",
        "cat3": "",
        "cat4": "indeclinable nouns",
        "g": "n",
        "g2": "",
        "g3": "",
        "head": "",
        "sort": "",
        "tr2": ""
      },
      "expansion": "πι • (pi) n (indeclinable)",
      "name": "head"
    },
    {
      "args": {
        "1": "n",
        "2": "inv"
      },
      "expansion": "πι • (pi) n (indeclinable)",
      "name": "el-noun"
    }
  ],
  "lang": "Greek",
  "lang_code": "el",
  "pos": "noun",
  "senses": [
    {
      "glosses": [
        "Letter pi"
      ],
      "links": [
        [
          "pi",
          "pi"
        ]
      ],
      "tags": [
        "indeclinable"
      ]
    },
    {
      "glosses": [
        "Used in \"στο πι και φι\" meaning at the drop of a hat."
      ],
      "links": [
        [
          "στο πι και φι",
          "στο πι και φι"
        ],
        [
          "at the drop of a hat",
          "at the drop of a hat"
        ]
      ],
      "tags": [
        "indeclinable"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/pi/"
    }
  ],
  "word": "πι"
}