Diagnosticate is a verb that is used to describe the process of identifying a disease or medical condition. Antonyms for this word include words that mean the opposite, such as ignore, neglect or overlook. These words all suggest a lack of attention or awareness, which can lead to a failure to diagnose a patient's condition. Other antonyms for diagnosticate include hesitate, doubt or speculate. These words suggest a lack of confidence or uncertainty, which can also interfere with accurate diagnosis. It is important for medical professionals to be diligent, attentive and confident in their diagnostic skills in order to properly diagnose and treat their patients.