Buddy means friend
A buddy is a measure or a friend, and is mainly used to indicate that it is someone who voluntarily helps another in a serious illness. A buddy offers a listening ear, talks about emotions and problems that the disease entails, and about other issues that are raised. A buddy also undertakes activities (if the disease permits), this can be a walk, go to the film or the theatre, or just drink something somewhere. Buddies also offer practical support such as going to the hospital, assisting other caregivers, etc.