Ancient of Days: An expression applied to Jehovah three times in the vision of Daniel (7:9, 13, 22) in the sense of eternal. In contrast with all earthly kings, his days are past reckoning.

Noah Webster's New International Dictionary of the English Language

1. (a.) Old; that happened or existed in former times, usually at a great distance of time; belonging to times long past; specifically applied to the times before the fall of the Roman empire; -- opposed to modern; as, ancient authors, literature, history; ancient days.

2. (a.) Old; that has been of long duration; of long standing; of great age; as, an ancient forest; an ancient castle.

3. (a.) Known for a long time, or from early times; -- opposed to recent or new; as, the ancient continent.

4. (a.) Dignified, like an aged man; magisterial; venerable.

5. (a.) Experienced; versed.

6. (a.) Former; sometime.

7. (n.) Those who lived in former ages, as opposed to the moderns.

8. (n.) An aged man; a patriarch. Hence: A governor; a ruler; a person of influence.

9. (n.) A senior; an elder; a predecessor.

10. (n.) One of the senior members of the Inns of Court or of Chancery.

11. (n.) An ensign or flag.

12. (n.) The bearer of a flag; an ensign.