Possible Clues:

• When tripled, a story shortener
• "Blah ..."
• "And so on," when tripled
• Said three times, a story shortener
• Word usually said in triplicate
• When tripled, a 'Seinfeld' catchphrase
• When repeated twice, et cetera
• When repeated, a 'Seinfeld' catchphrase
• When said thrice, "and so on"
• When tripled, 'et cetera'