In the Pali language, the term is Samatha (pronounced suh-muh-tuh). It is often translated into English as tranquility, calmness, or serenity.
The word itself comes from the root sam, which means to be quiet or to appease. In a meditative context, it refers to the "stilling" of the mind's constant chatter (often called the "monkey mind") to reach a state of deep peace and one-pointedness.
Tranquility meditation is the practice of training the mind to rest on a single object without wavering.
One-Pointedness (Ekaggatā): The primary goal is to unify the mind. Instead of the mind jumping between thoughts, memories, and worries, it becomes "fixed" on one thing.
The Object of Focus: To achieve this calm, practitioners use a "meditation subject" (kammaṭṭhāna). The most common is the breath (Anapanasati), but other objects include:
Visual objects (like a candle flame or a colored disc).
Mental recitations (like the word "Buddho" or "Peace").
Cultivating specific emotions (like Loving-Kindness or Metta).
The Resulting States (Jhāna): As the mind becomes exceptionally still and free from distractions, it may enter states of deep meditative absorption called Jhānas. These are characterized by intense joy, comfort, and eventually, profound equanimity.
While insight meditation (Vipassanā) is used to realize the nature of reality, Samatha acts as the essential foundation. Think of it like this:
If you want to see the bottom of a lake, the water must first be still.
Samatha is the act of stilling the water (the mind), so that Vipassanā (insight) can clearly see what lies beneath.
By calming the "five hindrances"—sensual desire, ill-will, sloth, restlessness, and doubt—Samatha creates a "workable" mind that is strong enough to handle the deep truths discovered in the second type of meditation.