IUM

Set to 4 different clues across 5 published puzzles, most often “Elemental ending” — The New York Times, Sunday, 16 January 2000.

3 letters

Every clue on record, most used first

Elemental ending2 times
The New York Times — Sunday, 16 January 2000
Common suffix on chemical elementsonce
The New York Times — Thursday, 10 July 2008
Elementary suffixonce
The New York Times — Sunday, 21 March 2004
Elementary endingonce
The New York Times — Sunday, 14 March 1999