[例]  The competition is very fierce.

competitor (n.) person/company that competes竞争者

[例]  Dozens of competitors are applying for the position of sales manager.

[同义词]  rival, opponent, adversary

competitive (adj.) of a product which competes well有竞争力的

[例]  It’s important to keep a competitive edge.

[同义词]  rival, competing, vying, combative

competitive edge (n.) advantage竞争优势

[例] We have competitive edge in this respect.

competitiveness (n.) process of being competitive 竞争力