(as) old as the hills
humorous Very old. Oh, she's old as the hills, she can't hear us. Why don't we ever sing new songs? Those hymns are as old as the hills.
*old as the hills
very old; ancient. (*Also: as ~.) That's not a new joke; it's as old as the hills! Our family custom of eating black-eyed peas on New Year's Day is old as the hills.
old as the hills
If something is as old as the hills, it is very old. Their equipment may be modern, but the techniques remain as old as the hills.
(as) old as the ˈhills
very old; ancient: That joke’s as old as the hills!