You are correct. You can use functions like Match() or Pos(). You can use MATCH([Dimension];"*def*")) and this will get you the output and wildcard will match the beginning of the string.
Pos Function is used to return the position of a specific character string.
You can also try using Pos() function as below −
=Pos("def abc ghi";"def") returns 1 =Pos("def abc ghi";"abc") returns 5 =Pos("def abc ghi";"xyz") returns 0