Buddha refers both to the historical man who was born in what is now southern Nepal and taught in northern India 2,600 years ago, and to awakening or enlightenment. The word literally means “one who is awake.”
Dhamma [Sanskrit: dharma] refers to the nature of things, natural law, or fundamental truth; the teachings of the Buddha; and the liberating path of practice.
Sangha means community. It customarily includes:
The communities of Buddhist monks and nuns
Those followers of the Buddha, lay or ordained, who have attained a level of realization and distinction that culminates in Nibbāna
The wider community of followers on the Buddhist path
In general usage we extend the definition to include all those who practice meditation together.