In this paper, we study the notion of T -noncosingular abelian
groups, which means an abelian group whose nonzero endomorphisms
are not small. We show that injective (divisible) and projective (free)
groups are T -noncosingular. We proved that T -noncosingular torsion
groups are exactly the direct sum of a semisimple group C and a divisible
group D which does not have simple subgroups isomorphic to a
subgroup of C. Many other interesting results are presented here, we
also give some condition for torsion-free groups to be T noncosingular
(Though torsion-free groups are K-noncosingular).
Keywords: Abelian group, Torsion group, Torsion-free group,
T-noncosingular, small homomorphims, small subgroup, simple group and
semi-simple group