Concise Bible Dictionary:
These are used symbolically in Ezekiel in connection with the living creatures of God’s providential administration on earth. The Spirit was in the wheels, and the wheels had the appearance of a beryl, and were full of eyes: typical of the controlled but intelligent motion of events: wheels were within wheels, which mark the control of the events as mysterious and hidden.
Strong’s Dictionary of Hebrew Words:
Meaning:
or (shortened) pophan {o-fawn'}; from an unused root meaning to revolve; a wheel