An omnibus clause is a clause that provides or includes all residuary not specifically mentioned.
A very common omnibus clause deals with automobile liability insurance. The clause provides coverage for the named insured, any member of the insured's household, and to any person using the automobile with the insured's permission, provided the use was within the permitted scope.
A second common omnibus clause is used in wills. The clause distributes to the named beneficiary all unnamed assets included in the decedent's estate.
References
Omnibus clause Wikipedia(Text) CC BY-SA