"-iβ̃" meaning in Proto-Brythonic

{
  "descendants": [
    {
      "depth": 1,
      "templates": [
        {
          "args": {
            "1": "owl",
            "2": "-im"
          },
          "expansion": "Old Welsh: -im",
          "name": "desc"
        }
      ],
      "text": "Old Welsh: -im"
    },
    {
      "depth": 2,
      "templates": [
        {
          "args": {
            "1": "wlm",
            "2": "-if",
            "3": "-i"
          },
          "expansion": "Middle Welsh: -if, -i",
          "name": "desc"
        }
      ],
      "text": "Middle Welsh: -if, -i"
    },
    {
      "depth": 3,
      "templates": [
        {
          "args": {
            "1": "cy",
            "2": "-i"
          },
          "expansion": "Welsh: -i",
          "name": "desc"
        }
      ],
      "text": "Welsh: -i"
    },
    {
      "depth": 1,
      "templates": [
        {
          "args": {
            "1": "xbm",
            "2": "-iff"
          },
          "expansion": "Middle Breton: -iff",
          "name": "desc"
        }
      ],
      "text": "Middle Breton: -iff"
    },
    {
      "depth": 2,
      "templates": [
        {
          "args": {
            "1": "br",
            "2": "-iñ"
          },
          "expansion": "Breton: -iñ",
          "name": "desc"
        }
      ],
      "text": "Breton: -iñ"
    },
    {
      "depth": 1,
      "templates": [
        {
          "args": {
            "1": "cnx",
            "2": "-y"
          },
          "expansion": "Middle Cornish: -y",
          "name": "desc"
        }
      ],
      "text": "Middle Cornish: -y"
    }
  ],
  "etymology_text": "From Insular Celtic *-īmā. Originally occurring in compounds *kreddīmā, *(ɸ)rodīmā, where the formation *dīmā, from Pre-Celtic *dʰeh₁meh₂, was resegmented as *-d-īmā. Supplanted *-ed and possibly *-id as the productive verbal noun formative for ī-verbs.",
  "head_templates": [
    {
      "args": {
        "1": "cel-bry-pro",
        "2": "suffix"
      },
      "expansion": "*-iβ̃",
      "name": "head"
    }
  ],
  "lang": "Proto-Brythonic",
  "lang_code": "cel-bry-pro",
  "original_title": "Reconstruction:Proto-Brythonic/-iβ̃",
  "pos": "suffix",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Proto-Brythonic entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "Forms verbal nouns, originally from ī-verbs."
      ],
      "id": "en--iβ̃-cel-bry-pro-suffix-70a9fB6D",
      "related": [
        {
          "word": "-aβ̃"
        },
        {
          "word": "-oβ̃"
        },
        {
          "word": "-ọβ̃"
        }
      ],
      "tags": [
        "morpheme",
        "reconstruction"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/iβ̃/"
    }
  ],
  "word": "-iβ̃"
}

{
  "descendants": [
    {
      "depth": 1,
      "templates": [
        {
          "args": {
            "1": "owl",
            "2": "-im"
          },
          "expansion": "Old Welsh: -im",
          "name": "desc"
        }
      ],
      "text": "Old Welsh: -im"
    },
    {
      "depth": 2,
      "templates": [
        {
          "args": {
            "1": "wlm",
            "2": "-if",
            "3": "-i"
          },
          "expansion": "Middle Welsh: -if, -i",
          "name": "desc"
        }
      ],
      "text": "Middle Welsh: -if, -i"
    },
    {
      "depth": 3,
      "templates": [
        {
          "args": {
            "1": "cy",
            "2": "-i"
          },
          "expansion": "Welsh: -i",
          "name": "desc"
        }
      ],
      "text": "Welsh: -i"
    },
    {
      "depth": 1,
      "templates": [
        {
          "args": {
            "1": "xbm",
            "2": "-iff"
          },
          "expansion": "Middle Breton: -iff",
          "name": "desc"
        }
      ],
      "text": "Middle Breton: -iff"
    },
    {
      "depth": 2,
      "templates": [
        {
          "args": {
            "1": "br",
            "2": "-iñ"
          },
          "expansion": "Breton: -iñ",
          "name": "desc"
        }
      ],
      "text": "Breton: -iñ"
    },
    {
      "depth": 1,
      "templates": [
        {
          "args": {
            "1": "cnx",
            "2": "-y"
          },
          "expansion": "Middle Cornish: -y",
          "name": "desc"
        }
      ],
      "text": "Middle Cornish: -y"
    }
  ],
  "etymology_text": "From Insular Celtic *-īmā. Originally occurring in compounds *kreddīmā, *(ɸ)rodīmā, where the formation *dīmā, from Pre-Celtic *dʰeh₁meh₂, was resegmented as *-d-īmā. Supplanted *-ed and possibly *-id as the productive verbal noun formative for ī-verbs.",
  "head_templates": [
    {
      "args": {
        "1": "cel-bry-pro",
        "2": "suffix"
      },
      "expansion": "*-iβ̃",
      "name": "head"
    }
  ],
  "lang": "Proto-Brythonic",
  "lang_code": "cel-bry-pro",
  "original_title": "Reconstruction:Proto-Brythonic/-iβ̃",
  "pos": "suffix",
  "related": [
    {
      "word": "-aβ̃"
    },
    {
      "word": "-oβ̃"
    },
    {
      "word": "-ọβ̃"
    }
  ],
  "senses": [
    {
      "categories": [
        "Proto-Brythonic entries with incorrect language header",
        "Proto-Brythonic lemmas",
        "Proto-Brythonic suffixes",
        "Proto-Brythonic terms with IPA pronunciation"
      ],
      "glosses": [
        "Forms verbal nouns, originally from ī-verbs."
      ],
      "tags": [
        "morpheme",
        "reconstruction"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/iβ̃/"
    }
  ],
  "word": "-iβ̃"
}