STUMPERS DXII

A Little Off the Sides

The word "gym" is a shortened form of the word "gymnasium," with the end chopped off. The word "bus" is a shortened form of "omnibus," with the front chopped off. Can you think of a common three-letter word that is a shortened form of a longer word in which both the front and end are chopped off? 

HINTS: 

1. The longer word has nine letters.

2.  _ _   XXX   _ _ _ _

Answer:

FLU - inFLUenza 

Credit:

Will Shortz