Definition from Wiktionary, the free dictionary
Alternative forms 
cutthroat (plural cutthroats)
unscrupulous, ruthless or unethical person
- Involving the cutting of throats
- Of or relating to a card game where everyone plays for him or herself rather than playing with a partner.
- He found that playing cutthroat Spades was much more difficult than playing with a partner.
- Ruthlessly competitive, dog-eat-dog
- Law is a cutthroat business, you always have to look out to see who is trying to outdo you.