Did You Know?
You might have trouble figuring out "gainsay" if you're thinking of our modern "gain" plus "say." It might help to know that the "gain-" part is actually related to "against." In Old English, "gēan-" meant "against." From that came the Middle English "gain-." "Gain-" was joined with "sayen" ("say") to form "gainsayen," the Middle English predecessor of "gainsay." So when you see "gainsay," think "say against" -- that is, "deny" or "contradict." When you do happen to come across "gainsay," it's likely to be in literature. "Gainsay" is a literary, somewhat old-fashioned word that isn't heard much in everyday modern speech.
*Indicates the sense illustrated in the example sentence.