Traditionally this word has been pronounced with stress on the second syllable. However, a newer pronunciation with stress on the first syllable has apparently gained a lot of ground and is now equally acceptable. In a recent ballot, 45 percent of the Usage Panel preferred the older pronunciation, and 50 percent preferred the newer one. A small percentage of the panelists use both pronunciations. Perhaps one reason for the shift is the association of aberrant with aberration and aberrated, which are both stressed on the first syllable.
