vice admiral

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A commissioned rank in the US Navy or Coast Guard that is above rear admiral and below admiral.
• noun One who holds this rank.

from The Century Dictionary.

• noun A degree of the rank of admiral. See admiral, 2.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun nautical A naval rank between rear admiral and admiral
• noun A flag officer in the United States Navy, Coast Guard, National Oceanic and Atmospheric Administration Commissioned Corps, or Public Health Service Commissioned Corps having a grade superior to rear admiral (upper half) and junior to admiral. A vice admiral is equal in grade or rank to a lieutenant general, which is indicated by a 3-star insignia.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun an admiral ranking below a full admiral and above a rear admiral