I think your this line is creating a problem:-
sql = "SELECT * FROM Words + Definitions"
I dont think that this is allowed. You cannot join tables using +(considering Words and Definitions as tables)
And if the table name is Words + Definitions the you may try this:-
sql = "SELECT * FROM [Words + Definitions]"
Also this line should be changes from
da.Fill(ds, "Words + Definitions")
to simple this:-
da.Fill(ds)