nosto-, nost- (Greek: return home).nostalgia: 
1. Longing to return home or to one's native land; homesickness.  
2. A mixed feeling of happiness, sadness, and longing when recalling a person, place, or event from the past. 3. Originally a medical term for a severe melancholia caused by protracted absence from home. nostologist: 
One who studies senility; a gerontologist.
 
nostology, nostologic: 
1. The study of the senile stages of an organism or race of organisms.  
2. The study of senility; gerontology. Based on the idea that some aspects of "later life [senility] is somewhat like returning to early years". nostomania: 
An intense form of nostalgia; an irresistible impulse to return home.
 
nostomaniac: 
Someone who has an irresistible desire to return home.
 
nostophobia: 
An abnormal fear of returning home.
 
nostos: 
A homecoming, applied specifically to the homeward journeys of Odysseus and the other heroes of Troy.
 
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