As defined by Freud, resistance refers to patients blocking memories from conscious memory. More generally, however, the term is used to describe the direct or indirect opposition of a patient to the therapeutic process.
Usually, the resistance begins when the therapist is very close to the source of the main issue that the client is in therapy for. The person will then start to demonstrate characteristics that are not usual for them such as anger towards the therapist or convenient forgetful moments when asked about a certain topic. Typically, the symptom of resistance implies that the therapy is working.
Example: A patient who is otherwise extremely organized repeatedly cancels or forgets therapy appointments.
Fournier, G. (2016). Resistance. Psych Central. Retrieved on February 18, 2017, from https://psychcentral.com/encyclopedia/resistance/