In technical and scientific terms:
- pro- (prefix): in favour of, supporting, acting on behalf of.
- Protagonist: the leading character or the one who is prominent in a drama, film or other work of fiction.
- Prokaryote: an organism that lacks a nucleus or any other membrane-bound organelles.
- Protein: a molecule that consists of a long chain of amino acids.
- Processor: the part of a computer that controls the execution of instructions.
- Produce: to make or manufacture something.
- Professional: a person who is engaged in a profession or who is proficient in a particular field of activity.
- Program: a set of instructions that tells a computer what to do.
- Project: a planned undertaking, especially one involving considerable effort or expense.
In general usage:
- Pro (noun): a person who is in favor of something or who supports a particular cause, as opposed to someone who is con (against)
- Pro (adverb): in a professional manner or style.