Say I'm describing what a program does. Say it converts roman numerals to decimal and decimal to Roman numeral.

I could say, in the description, "Converts from Roman numerals to decimals and from decimals to Roman numerals". I could also say "Converts from Roman numerals to decimals and [blank]". It's not conversely or likewise. What is the word, I know what it is but cannot remember?


In English, we often use the Latin phrase Vice Versa for this.

Excerpts from Wiktionary which licenses its text under CC-BY-SA 3.0 terms has the following definition:

Adverb vice versa (not comparable) The same but with the two things or people mentioned reversed.

As long as my friend Mike places first and my friend Joe places second, or vice versa, I will be happy!

And also the following etymology.

Etymology From Latin ablative absolute vice versā (“the position having been reversed”), from feminine third declension noun vicis (“arrangement, order, position, etc.”) + feminine ablative singular of perfect passive participle versus, from vertō (“I turn, I reverse”).

If you do not trust wiktionary, similar definitions can be found in The American Heritage Dictionary, 5th edition, Collins English Dictionary—Complete and Unabridged 12th edition and Random House Kernerman Webster's College Dictionary ©2010 as shown by The Free Dictionary by Farlex.

A few examples of actual use in actual English can be found in the New York State Department of Labor's Annual report, Volume 1 from 1907, including but not limited to the following example:

Through slow freight service, Coxton to Lehighton or Mahoning and return, or vice versa, two dollars and ninety cents ($2.90) per round trip. Overtime after fifteen (15) hours and thirty (30) minutes.

As a side note, Wiktionary also shows that vice versa is sometimes misspelled visa versa, which I personally find to be more recognizable, if that helps to ring any bells for you.


"Back" is the word you're looking for.

Some possible ways to write it:

  • Converts from Roman numerals to decimals and back.
  • Converts to and from Roman numerals.
  • Converts to/from Roman numerals.
  • 1
    I thought that at first but it's not quite true. Back in this sense would imply that the conversion always starts with Roman numerals and can then be reversed. The application described allows the transcription to be started from either representation and to end with the new representation, eg turning 2017 into MMXVII or MCML into 1950 I prefer Vice Versa as suggested by @tonepoet above.
    – BoldBen
    Nov 3 '17 at 10:15