<unk>  means related to aging. For example,<unk>  weakness is a form of weakness happening in old people.
The word<unk>  comes from the latin sen meaning "old". This word was first coined in 1661. In Persian language, "سن" (pronounced as "sen") means "age".<unk>  may also refer to Dementia, which is a disease typically seen in the elderly.
Senile
Acute 
Chronic 
Grief
Pagetoid
Deaf-mute
Hydrophile
Dementia causes