Definers Public Affairs was an American right leaning opposition research firm based in Arlington, Virginia. It performed media monitoring services, conducted research using the Freedom of Information Act and also created strategic communication to negatively influence the public image about individuals, firms, candidates and organizations who oppose their clients. Definers shared at least nine current and former executives, as well as its office space, with America Rising, a Republican-affiliated political action committee, and NTK Network, a digital news aggregator.