"-ech" meaning in Old Irish

{
  "head_templates": [
    {
      "args": {
        "1": "sga",
        "2": "suffix form"
      },
      "expansion": "-ech",
      "name": "head"
    }
  ],
  "lang": "Old Irish",
  "lang_code": "sga",
  "pos": "suffix",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Old Irish entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 4 entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "_dis": "0 0 5 29 33 15 17",
          "kind": "other",
          "name": "Entries with collapsible category trees for nonexistent categories",
          "parents": [],
          "source": "w+disamb"
        },
        {
          "_dis": "0 0 16 24 40 10 10",
          "kind": "other",
          "name": "Pages using catfix",
          "parents": [],
          "source": "w+disamb"
        },
        {
          "_dis": "0 0 6 42 45 4 4",
          "kind": "other",
          "name": "Pages with 4 entries",
          "parents": [],
          "source": "w+disamb"
        },
        {
          "_dis": "0 0 5 43 45 3 3",
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w+disamb"
        }
      ],
      "form_of": [
        {
          "word": "-ach used after a palatalised consonant"
        }
      ],
      "glosses": [
        "Form of -ach used after a palatalised consonant."
      ],
      "id": "en--ech-sga-suffix-mVgpsi5-",
      "links": [
        [
          "-ach",
          "-ach#Old_Irish"
        ]
      ],
      "tags": [
        "form-of",
        "morpheme"
      ]
    }
  ],
  "word": "-ech"
}

{
  "categories": [
    "Entries with collapsible category trees for nonexistent categories",
    "Pages using catfix",
    "Pages with 4 entries",
    "Pages with entries"
  ],
  "head_templates": [
    {
      "args": {
        "1": "sga",
        "2": "suffix form"
      },
      "expansion": "-ech",
      "name": "head"
    }
  ],
  "lang": "Old Irish",
  "lang_code": "sga",
  "pos": "suffix",
  "senses": [
    {
      "categories": [
        "Old Irish entries with incorrect language header",
        "Old Irish non-lemma forms",
        "Old Irish suffix forms",
        "Pages with 4 entries",
        "Pages with entries"
      ],
      "form_of": [
        {
          "word": "-ach used after a palatalised consonant"
        }
      ],
      "glosses": [
        "Form of -ach used after a palatalised consonant."
      ],
      "links": [
        [
          "-ach",
          "-ach#Old_Irish"
        ]
      ],
      "tags": [
        "form-of",
        "morpheme"
      ]
    }
  ],
  "word": "-ech"
}