Find a way to have a multi select field

[illan....@gmail.com]

Hello,

I am trying to find a way to have a field with a multi select proposal.
The only way I find is to create a string or text field multi valued and to link this field to the Thesaurus. But the issue I have is that I am not only able to select more than one value from the thesaurus.
Did some one have an idea or a solution ?

Many thanks in advance,
Illan