Synonyms: Strong immune system, Immune to Poison, Immune to Diseases
The character is particularly resistant to diseases, infections and poisons.
Whether it is innate or acquired (having for example survived the plague or a particularly serious infection), or that it is both, the character is almost immune to diseases, infections and poisons when compared to ordinary mortals.
It is almost impossible for him to be contaminated by a disease, and when he is, the symptoms will be less heavy and he will heal much faster (or will have a much better chance of healing) compared to a normal person .
Same applies for poisons.