What does it mean to have acquired immunological tolerance?

Immune tolerance: This term can be applied to many different situations. It could be used to describe the lack of a rejection reaction after an organ transplant, (i.E the host immune system is no longer trying to destroy the foreign organ). It could also be used to describe the lack of an allergic reaction to an allergen expos observed following the sucessful treatment of allergies with allergy shots (immunotherapy.

No longer allergic: Immunolgic tolerance is achieved when your immune system no longer recognizes a substance as foreign, and stops reacting negatively to it.