State your version.
Filemaker Pro 11.0v1 Mac Os X 10.6.3
In version 11, you can place a portal to Synonyms on a layout of Products, and filter it to show only records where:
Synonyms::Company = "Some Company"
actually I need it to create a file excel which will be used by purchase department to order the same product to different suppliers (different companies and so different synonyms/codes). I'm trying to use filemaker because I'm drowning in a sea of multiple files with excel and I'm not using forms. I used a little 4D in the past and I know you were able to create and name set/subsets and to use them for looking values up
OK, if that's where you going, you should start by adding a table of Suppliers and linking it to the Synonyms table by SupplierID, so that your Synonyms table has these fields:
Then you can link your order items table to Synonyms by matching on both ProductID and SupplierID, and get the appropriate name via this relationship.
Doesn't look like you need an actual lookup here - unless suppliers change their product names and you need to preserve the historical name in the existing orders.