The correct legal answer is "that depends." When filing a trademark application, it's best to hire a TM attorney because the "if-then" scenarios are plentiful. The most basic test is one of likelihood of confusion. Trademarks serve to identify the source of a particular good or service. If your trademark is likely to cause confusion between the source of your good or service and that of another person, there could be trouble. Each trademark case is unique and must be analyzed under it's own particular facts.