'Old' in the Bible

Ishbosheth Saul's son was forty years old when he began to reign over Israel, and reigned two years. But the house of Judah followed David.

And Jonathan, Saul's son, had a son that was lame of his feet. He was five years old when the tidings came of Saul and Jonathan out of Jezreel, and his nurse took him up, and fled: and it came to pass, as she made haste to flee, that he fell, and became lame. And his name was Mephibosheth.

David was thirty years old when he began to reign, and he reigned forty years.

Now Tamar was wearing a [long-sleeved] robe of various colors; for that is how the virgin daughters of the king dressed themselves in robes. Then Amnon’s personal servant took her out and bolted the door behind her.

Now Barzillai was a very aged man, even fourscore years old: and he had provided the king of sustenance while he lay at Mahanaim; for he was a very great man.

I am this day fourscore years old: and can I discern between good and evil? can thy servant taste what I eat or what I drink? can I hear any more the voice of singing men and singing women? wherefore then should thy servant be yet a burden unto my lord the king?

Then she spake, saying, They were wont to speak in old time, saying, They shall surely ask counsel at Abel: and so they ended the matter.