Samatha is the development of calm, through concentration on a single object such as the breath, a coloured disc or loving-kindness. It suppresses the hindrances and leads to the absorptions. Buddhist teachers pair it with vipassanā, insight, and most hold that both are needed.
Samatha
Calm or tranquillity: meditation that stills and unifies the mind, leading to absorption.
Also: Shamatha, calm abiding