"u" meaning in Old Czech

{
  "descendants": [
    {
      "depth": 1,
      "templates": [
        {
          "args": {
            "1": "cs",
            "2": "u"
          },
          "expansion": "Czech: u",
          "name": "desc"
        }
      ],
      "text": "Czech: u"
    }
  ],
  "etymology_number": 1,
  "etymology_templates": [
    {
      "args": {
        "1": "zlw-ocs",
        "2": "sla-pro",
        "3": "*u"
      },
      "expansion": "Proto-Slavic *u",
      "name": "inh"
    }
  ],
  "etymology_text": "Inherited from Proto-Slavic *u.",
  "head_templates": [
    {
      "args": {
        "1": "zlw-ocs",
        "2": "prepositions"
      },
      "expansion": "u",
      "name": "head"
    }
  ],
  "lang": "Old Czech",
  "lang_code": "zlw-ocs",
  "pos": "prep",
  "senses": [
    {
      "categories": [
        {
          "_dis": "61 39",
          "kind": "other",
          "name": "Old Czech entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        },
        {
          "_dis": "64 36",
          "kind": "other",
          "name": "Old Czech prepositions",
          "parents": [],
          "source": "w+disamb"
        }
      ],
      "glosses": [
        "Denotes approximate location; by, at; with [+genitive]",
        "Denotes approximate location; by, at; with"
      ],
      "id": "en-u-zlw-ocs-prep-hDQYy7aU",
      "links": [
        [
          "by",
          "by"
        ],
        [
          "at",
          "at"
        ],
        [
          "with",
          "with"
        ]
      ],
      "raw_glosses": [
        "Denotes approximate location; by, at; with [+genitive]"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/ˈu/",
      "note": "13ᵗʰ CE"
    },
    {
      "ipa": "/ˈu/",
      "note": "15ᵗʰ CE"
    }
  ],
  "word": "u"
}

{
  "etymology_number": 2,
  "head_templates": [
    {
      "args": {
        "1": "zlw-ocs",
        "2": "prepositions"
      },
      "expansion": "u",
      "name": "head"
    }
  ],
  "lang": "Old Czech",
  "lang_code": "zlw-ocs",
  "pos": "prep",
  "senses": [
    {
      "alt_of": [
        {
          "extra": "often before labial consonants",
          "word": "v"
        }
      ],
      "glosses": [
        "Alternative form of v (often before labial consonants)"
      ],
      "id": "en-u-zlw-ocs-prep-f1ZAaBeI",
      "links": [
        [
          "v",
          "v#Old Czech"
        ]
      ],
      "tags": [
        "alt-of",
        "alternative"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/ˈu/",
      "note": "13ᵗʰ CE"
    },
    {
      "ipa": "/ˈu/",
      "note": "15ᵗʰ CE"
    }
  ],
  "word": "u"
}

{
  "categories": [
    "Old Czech entries with incorrect language header",
    "Old Czech lemmas",
    "Old Czech prepositions",
    "Old Czech terms derived from Proto-Slavic",
    "Old Czech terms inherited from Proto-Slavic",
    "Old Czech terms with IPA pronunciation",
    "Pages with raw sortkeys"
  ],
  "descendants": [
    {
      "depth": 1,
      "templates": [
        {
          "args": {
            "1": "cs",
            "2": "u"
          },
          "expansion": "Czech: u",
          "name": "desc"
        }
      ],
      "text": "Czech: u"
    }
  ],
  "etymology_number": 1,
  "etymology_templates": [
    {
      "args": {
        "1": "zlw-ocs",
        "2": "sla-pro",
        "3": "*u"
      },
      "expansion": "Proto-Slavic *u",
      "name": "inh"
    }
  ],
  "etymology_text": "Inherited from Proto-Slavic *u.",
  "head_templates": [
    {
      "args": {
        "1": "zlw-ocs",
        "2": "prepositions"
      },
      "expansion": "u",
      "name": "head"
    }
  ],
  "lang": "Old Czech",
  "lang_code": "zlw-ocs",
  "pos": "prep",
  "senses": [
    {
      "glosses": [
        "Denotes approximate location; by, at; with [+genitive]",
        "Denotes approximate location; by, at; with"
      ],
      "links": [
        [
          "by",
          "by"
        ],
        [
          "at",
          "at"
        ],
        [
          "with",
          "with"
        ]
      ],
      "raw_glosses": [
        "Denotes approximate location; by, at; with [+genitive]"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/ˈu/",
      "note": "13ᵗʰ CE"
    },
    {
      "ipa": "/ˈu/",
      "note": "15ᵗʰ CE"
    }
  ],
  "word": "u"
}

{
  "categories": [
    "Old Czech entries with incorrect language header",
    "Old Czech lemmas",
    "Old Czech prepositions",
    "Old Czech terms with IPA pronunciation",
    "Pages with raw sortkeys"
  ],
  "etymology_number": 2,
  "head_templates": [
    {
      "args": {
        "1": "zlw-ocs",
        "2": "prepositions"
      },
      "expansion": "u",
      "name": "head"
    }
  ],
  "lang": "Old Czech",
  "lang_code": "zlw-ocs",
  "pos": "prep",
  "senses": [
    {
      "alt_of": [
        {
          "extra": "often before labial consonants",
          "word": "v"
        }
      ],
      "glosses": [
        "Alternative form of v (often before labial consonants)"
      ],
      "links": [
        [
          "v",
          "v#Old Czech"
        ]
      ],
      "tags": [
        "alt-of",
        "alternative"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/ˈu/",
      "note": "13ᵗʰ CE"
    },
    {
      "ipa": "/ˈu/",
      "note": "15ᵗʰ CE"
    }
  ],
  "word": "u"
}