risk arbitrage vs arbitrage

risk arbitrage and arbitrage both are nouns.

Word	Noun	Adjective	Verb	Adverb
risk arbitrage	Yes	No	No	No
arbitrage	Yes	No	Yes	No

As nouns, arbitrage is a hypernym of risk arbitrage; that is, arbitrage is a word with a broader meaning than risk arbitrage:

risk arbitrage: arbitrage involving risk; as in the simultaneous purchase of stock in a target company and sale of stock in its potential acquirer; if the takeover fails the arbitrageur may lose a great deal of money
arbitrage: a kind of hedged investment meant to capture slight differences in price; when there is a difference in the price of something on two different markets the arbitrageur simultaneously buys at the lower price and sells at the higher price

risk arbitrage (noun)	arbitrage (noun)
arbitrage involving risk; as in the simultaneous purchase of stock in a target company and sale of stock in its potential acquirer; if the takeover fails the arbitrageur may lose a great deal of money	a kind of hedged investment meant to capture slight differences in price; when there is a difference in the price of something on two different markets the arbitrageur simultaneously buys at the lower price and sells at the higher price

risk arbitrage (verb)	arbitrage (verb)
	practice arbitrage, as in the stock market