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

  • noun An argument or consideration in favor of something.
  • noun One who supports a proposal or takes the affirmative side in a debate.
  • adverb In favor; affirmatively.
  • adjective Affirmative; supporting.
  • noun A professional, especially in sports.
  • noun An expert in a field of endeavor.
  • adjective Professional.

from The Century Dictionary.

  • noun A prefix of Latin or Greek origin, meaning ‘before,’ ‘in front,’ ‘fore,’ ‘forth,’ ‘forward.’ In some words, as proconsul, proprætor, pronoun, etc., it is properly the preposition (Latin pro, for, instead of).
  • noun A Latin preposition occurring in several phrases used in English.

from the GNU version of the Collaborative International Dictionary of English.

  • adverb For, on, or in behalf of, the affirmative side; -- in contrast with con.
  • adverb for and against, on the affirmative and on the negative side; ; -- formerly used also as a verb.
  • adverb the arguments or reasons on either side.
  • preposition A Latin preposition signifying for, before, forth.
  • preposition (Law) taken as confessed. The action of a court of equity on that portion of the pleading in a particular case which the pleading on the other side does not deny.
  • preposition In proportion; proportion.
  • preposition (Law) for the existing occasion; as matters are.

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

  • abbreviation ISO 639 code for Old Provençal
  • noun a professional sportsman
  • noun colloquial professional someone who is very good at something
  • noun an advantage of something, especially when contrasted with its disadvantages (cons).
  • preposition In favor of
  • noun A prostitute.

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

  • adverb in favor of a proposition, opinion, etc.
  • noun an argument in favor of a proposal
  • adjective in favor of (an action or proposal etc.)
  • noun an athlete who plays for pay


from The American Heritage® Dictionary of the English Language, 4th Edition

[Middle English, from Latin prō, for; see per in Indo-European roots.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

from Provencal

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Latin prō ("on behalf of").

from Wiktionary, Creative Commons Attribution/Share-Alike License



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  • "About 15 years later, Loeb had another brain wave. He realised that their design could be exploited to generate power. Working at Ben-Gurion University of the Negev, in Beer Sheva, Israel, he envisaged a tank with two chambers separated by a semipermeable membrane. With saltwater on one side and fresh on the other, osmosis would draw fresh water into the salty side, raising its pressure. This pressurised saltwater could then be piped through a turbine to generate electricity (see diagram). Loeb named this process pressure retarded osmosis (PRO) and patented it in 1973."

    - Kate Ravilious, Salt solution: Cheap power from the river's mouth,, 25 Feb 2009.

    April 8, 2009