symmetric monoidal (∞,1)-category of spectra
An ordinary group is either an abelian group or not. For an ∞-group there is an infinite tower of notions ranging from completely non-abelian to completely abelian. An abelian ∞-group is one which is maximally abelian. This is equivalently a connective spectrum object.
A 0-truncated abelian -group is equivalently an abelian group.
A 1-truncated abelian -group is equivalently a symmetric 2-group.
A 2-truncated abelian -group is equivalently a symmetric 3-group.
abelian ∞-group
Section 5 of