Dharma (the teaching)
One word for both the Buddha's teaching and the truth it points at, the way a map matches the territory.
Dharma (Sanskrit dharma, Pali dhamma) is one of the most important and many-sided words in Buddhism. In its central religious sense it means the Buddha's teaching, the whole body of guidance he gave about suffering and the way out of it. But it carries a second, deeper sense at the same time: the truth or natural order that the teaching points to, the way things actually are. The teaching and the reality it describes share one name because Buddhists understand the teaching to be an accurate map of the actual territory of existence, not a set of arbitrary doctrines.
Dharma is one of the "Three Jewels" that define Buddhist commitment, alongside the Buddha (the awakened teacher) and the Sangha (the community of practitioners). When Buddhists "go for refuge" to these three, taking refuge in the Dharma means relying on this teaching-and-truth as a trustworthy guide out of confusion and suffering.
The word is used flexibly. Sometimes it means the natural law or order of things in general; in some technical contexts (the same word in the plural, dharmas) it even means the basic momentary building-blocks of experience that some Buddhist analysts identified. But for most people, on most occasions, "the Dharma" simply means the Buddha's path and the liberating truth it conveys, something to be studied, practiced, and tested in one's own life rather than merely believed. A useful first definition is: the Dharma is reality as it is, together with the teaching that helps us see it.
Key passages(20)
The Buddha and His Dhamma · B. R. Ambedkar
The Dhammapada · Balangoda Ananda Maitreya
The Nyingma School of Tibetan Buddhism: Its Fundamentals and History · Dudjom Rinpoche (Jigdral Yeshe Dorje)
The Dhammapada: A New Translation of the Buddhist Classic with Annotations · Gil Fronsdal
Buddhist Dictionary: Manual of Buddhist Terms and Doctrines · Nyanatiloka Mahāthera
Old Path White Clouds: Walking in the Footsteps of the Buddha · Thich Nhat Hanh
太虛大師全書.第一編 佛法總學(第1卷-第26卷) · The Chinese Buddhist Canon (大藏經)
妙法蓮華經要解(選錄「要解」本文)(第1卷-第12卷) · The Chinese Buddhist Canon (大藏經)
The Secrets of the Realized Ones · The Tibetan Kangyur (84000)
The Teaching of Vimalakīrti · The Tibetan Kangyur (84000)