In response to a freedom of information request, the department posted its Analyst's Desktop Binder (a manual for the agency's security analysts) containing this hotlist. The keywords cover domestic security, HAZMAT and nuclear, health concern, infrastructure security and other threats.
According to the Daily Mail, the Department of Homeland Security says it only uses this keyword list to look for genuine security threats, not signs of general dissent. Nobody wants Big Brother looking over her shoulder—and you shouldn't have to feel like you need to censor yourself in this way—but if you're particularly paranoid about the government spying on you, you might reconsider using too many of these keywords together when you post something online. Here's the full list:
