Muteness or mutism is defined as an absence of speech while conserving or maintaining the ability to understand the speech of others. Mutism is typically understood as an inability to speak on the part of a child or an adult due to an observed lack of speech from the point of view of others who know them. Such observers commonly include a mute person's family members, caregivers, teachers, and health professionals like doctors or speech and language pathologists. Muteness may not be a permanent condition, depending upon etiology (cause). In general, someone who is mute may be mute for one of several different reasons: organic, psychological, developmental/ neurological. For children, a lack of speech may be developmental, neurological, psychological, or due to a physical disability or a communication disorder. For adults who previously had speech and then became unable to speak, loss of speech may be due to injury, disease, termed aphasia, or surgery affecting areas of the brain needed for speech. Loss of speech in adults may occur rarely for psychological reasons.