It is not actually Castilian but Basque, where Basque/Sunemi means "volcano". However we find it as the name of hotels, hockey teams, and medical associations.
It is a community organization of Basque origin and that aims to promote a new culture of health, seeking it to be more public and universal, more humane and more ecological. It is also the name of a football team from that same region.
SUMENDI partnership for self-management of health, which aims to empower people, promote self-healing power and consider the environmental and economic factors that influence it. Founded in 1986 in Euskal Herria.