cutthroat competition

Opposition that is especially fierce, relentless, or merciless. These school election breed some cutthroat competition. The students here will do just about anything to win, even if it means ruining each other's reputations. I never could handle the cutthroat competition of investment banking, so I decided to pursue something a bit more easygoing. You won't make it in Hollywood on talent alone—it's nothing but cutthroat competition.

cutthroat prices

Extremely low prices (i.e., those that "cut the throats" of competitors by being impossible to beat). They gained a huge foothold in the market by offering decent mid-range smartphones at cutthroat prices. We just can't compete with that discount supermarket and their cutthroat prices! I understand that they sell their products at cutthroat prices, but you don't usually get great quality for cheap.

cut someone's throat

1. Be the means of someone's ruin, as in Joe would cut her throat if she got in his way. One can also cut one's own throat, that is, spoil one's own chances, as in Alice cut her own throat by her repeated absences. This hyperbolic term alludes to actual murder (or suicide). [c. 1500]

2. cut one another's throats. Engage in destructive competition. For example, With their price war the two stores were cutting each other's throats. This usage gave rise, by 1880, to the idiom cutthroat competition, for vicious competitive practices.