Final answer:
An enlightened Theravadin Buddhist monk is called an Arahat, a person who has achieved enlightenment and reached the state of Nirvana. This is attained through meditation, mindfulness, and insight into the true nature of reality, following the Buddhist path outlined in the Eightfold Path and the Four Noble Truths.
Step-by-step explanation:
An enlightened Theravadin Buddhist monk is referred to as an Arahat or Arahant. In Theravada Buddhism, which is the oldest branch of Buddhism, an Arahat is a person who has attained enlightenment, the ultimate goal and the end of suffering.
Theravada Buddhism focuses on meditation and following the Buddha's original teachings to attain enlightenment. An enlightened individual, through insight, mindfulness, and deep concentration, realizes the true nature of reality, which includes the impermanence of all things, the non-existence of a permanent self, and the causes of suffering. Once a person attains enlightenment, they have reached the state of Nirvana and will no longer be subject to the cycle of rebirth and suffering.