(as) old as Adam
humorous Very old. An allusion to Adam, the first human created by God in the Bible. Oh, she's old as Adam, she can't hear us. Why don't we ever sing new songs? Those hymns are as old as Adam.
as old as Adam
Extremely ancient, well known long ago. The Adam reference, of course, is to the first book of the Bible, in which Adam is the first human being created by God. The OED traces the expression only to 1867. Similar clichés include old as the hills and from time immemorial. See also know (someone) from Adam.