o ‧ mis ‧ sion /əʊˈmɪʃ ə n, ə- $ oʊ-, ə-/ BrE AmE noun
1 . [uncountable] when you do not include or do not do something
omission of
The omission of her name was not a deliberate act.
omission from
his omission from the team
2 . [countable] something that has been omitted:
Copies of the lists were posted so that omissions could be corrected.
serious/notable/major omission
Your failing to note her mistakes is a serious omission.
a glaring omission (=one that is very bad and easily noticed)