The phrase "major omission" refers to a significant or important thing that has been left out or forgotten. It means that something crucial or essential has been overlooked or excluded. Full definition
There's no NFC on the phone, but that isn't as major an omission as it is in Western markets. (androidcentral.com)
«New study shows major omission in evidence of «weekend effect» on mortality rates in hospitals.» (sciencedaily.com)
Perhaps in an attempt to stay relevant in the age of the Apple Watch 3, Fitbit has ensured the Versa is brimming with fitness features, just like it did with the Fitbit Ionic, with the only major omission being GPS. (techradar.com)