The phrase "big deterrent" refers to something that strongly discourages or prevents someone from doing something because of the negative consequences or risks associated with it. Full definition
This is the single biggest deterrent to most people. (dealsagar.com)
Despite what was said at the Republican National Convention in Cleveland last week, the biggest deterrent to oil and gas production in the United States is price, not overregulation. (fortune.com)
«That's a big deterrent in identity theft cases; if an employee feels like the company cares for them, they're less likely to take advantage of the situation.» (cnbc.com)