Seasonal adjustment
Also called seasonally adjusted.
A statistical method that removes regular seasonal patterns, so changes from one month to the next are easier to compare.
BLS publishes the CPI both seasonally adjusted and not. The monthly changes in its release are seasonally adjusted; the 12-month change is not. Source 1 Source 2
Seasonally adjusted figures are revised as seasonal factors are recalculated. For the CPI, BLS revises them for up to five years. Source 1