Refers to a person or entity competing in business, sports, or other contests. Slightly formal; ライバル is more common in casual contexts.
We want to get ahead of our competitors with the new product.
He defeated his long-time rival and won the championship.
Compound of 競合 (competition, contention) + 者 (person). The exact historical derivation is uncertain, but the word follows a standard Sino-Japanese pattern for forming agent nouns.