I've been complaining about this word for a long time -- ever since I was an editor at Business Wire where it seemed that every single press release I read said that something "underscores our commitment." Despite its usefulness the first jillion times it's used, this expression became as tired and meaningless as "Have a nice day" or "Employees must wash hands before returning to work."
Then, on Saturday night, I was at a performance by the Groundlings -- a local improv and sketch troupe. Director Karen Maruyama was setting up an improv scene in which two actors had to perform a very mundane task -- scrapbooking -- in high-intensity Mission Impossible style. Karen turned to the pit musicians, asking them to "underscore" the scene with action-scene-type music.
In all my years of criticizing the overuse of this word, I never once noticed its musical implications. If you can score a film, it seems pretty natural that you might underscore a scene. Suddenly, I had a whole new appreciation of underscore.
Unfortunately, most dictionaries don't share my appreciation. Webster's New World College lists just one definition underscore: "a line drawn under a word, passage, etc., as for emphasis."
A Dictionary.com search shows that American Heritage Dictionary says it means just to "underline," "emphasize" or "stress."
Dictionary.com's own database is the only one that specifically mentions the word's musical implications: definition No. 4: "music for a film soundtrack; background for a film or stage production."
Of course, this does little to underscore my reasons for ceasing to hate underscore.