unknownorigin
nounUK /ʌnˈnəʊn ˈɒrɪdʒɪn/
US /ʌnˈnoʊn ˈɔːrɪdʒɪn/
A thing whose beginning is a mystery and nobody knows where it came from.
The strange rock in the garden was of unknownorigin, so the children made up stories about it.
OTHER MEANINGS
2. A word or name whose history cannot be traced.
The word's unknownorigin made it hard for the linguist to explain.
3. A person whose family background is not known.
The orphan was described as of unknownorigin in the old records.
4. A disease or illness with no clear cause.
The doctor noted the fever was of unknownorigin and ordered more tests.