The Greek word here is phiale, from which we get "vial." Some translators render it "bowl," others "censer." The exact form of the container is unknown, though it might even be thought of as a large urn, overflowing with God's long restrained wrath.

Source:

KJV Defenders Study Bible, by Dr. Henry Morris, Ph.D.
Publisher: Thomas Nelson
Language: English
DEF 10 ISBN 0-529-10444-x
DEF 10-1 ISBN 0-529-10445-8