/ Dictionary / Index A ad valorem: Meaning and Definition of Find definitions for: ad va•lo•rem Pronunciation: (ad vu-lôr'um, -lōr'-), [key] in proportion to the value (used esp. of duties on imports that are fixed at a percentage of the value as stated on the invoice). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. ad val. ad valorem tax Related Content Daily Word Quiz: sumptuous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language