this makes me think there might be too much to put in the second column of a combobox but you can always try.

Put an activeX combobox on the sheet. Set its properties ie: size, columncount, font size, listfillrange, etc.
Use a macro such as Worksheet_SelectionChange to set its visibile and location properties.
Then the comboboxes change event to write to the sheet and hide the combobox.

I've never had much success working with controls on a sheet and with data validation the font size is always an issue.

I'd probably use Worksheet_SelectionChange to bring up a user form that has the definitions easy to read along with option buttons or check boxes for the user to make their selection and then write back to the target cell.