Old is the most straightforward term to use when referring to advanced age. It strongly suggests at least a degree of physical infirmity and age-related restrictions. Although people often claim to find euphemisms more offensive than direct speech, you should be careful in labeling a person or group as old on the basis of chronological age alone. Where inappropriate, as with people just reaching retirement age and those leading active lives, or where bluntness might offend, you would do well to consider a less definitive term such as elderly or older.
