Sadguru, Shadguru: 12 definitions
Introduction:
Sadguru means something in Buddhism, Pali, Hinduism, Sanskrit, Marathi. If you want to know the exact meaning, history, etymology or English translation of this term then check out the descriptions on this page. Add your comment or reference to a book if you want to contribute to this summary article.
In Hinduism
Purana and Itihasa (epic history)
Source: archive.org: Shiva Purana - English TranslationSadguru (सद्गुरु) refers to a “good preceptor”, according to the Śivapurāṇa 2.1.12, while explaining details of worship:—“[...] the root of devotion (bhakti) is good action (satkarma) and the worship of one’s own favourite deity (iṣṭadeva). The root of that is the good preceptor. A good preceptor (sadguru) is secured only through association with good people (satsaṃgati). If one associates with good people, one will come across a preceptor. From the preceptor mantras and the modes of worship can be learned. Bhakti (devotion) is generated by worship and it gives birth to knowledge”.

The Purana (पुराण, purāṇas) refers to Sanskrit literature preserving ancient India’s vast cultural history, including historical legends, religious ceremonies, various arts and sciences. The eighteen mahapuranas total over 400,000 shlokas (metrical couplets) and date to at least several centuries BCE.
Vaishnavism (Vaishava dharma)
Source: Pure Bhakti: Bhagavad-gita (4th edition)Sadguru (सद्गुरु) refers to “bona fide spiritual master; spiritual preceptor who follows sat (the pure path of the sādhus as described within scripture and as delivered through paramparā)”. (cf. Glossary page from Śrīmad-Bhagavad-Gītā).
Source: Pure Bhakti: Brhad BhagavatamrtamSadguru (सद्गुरु) refers to:—Bona fide spiritual master. (cf. Glossary page from Śrī Bṛhad-bhāgavatāmṛta).

Vaishnava (वैष्णव, vaiṣṇava) or vaishnavism (vaiṣṇavism) represents a tradition of Hinduism worshipping Vishnu as the supreme Lord. Similar to the Shaktism and Shaivism traditions, Vaishnavism also developed as an individual movement, famous for its exposition of the dashavatara (‘ten avatars of Vishnu’).
Shaktism (Shakta philosophy)
Source: Google Books: ManthanabhairavatantramSadguru (सद्गुरु) refers to a “true teacher”, according to the Manthānabhairavatantra, a vast sprawling work that belongs to a corpus of Tantric texts concerned with the worship of the goddess Kubjikā.—Accordingly, “The teacher in the western house is one who belongs to the sequence of the line (of teachers). [...] He practices his meditation in each house and that utterance (of mantra) in particular. (His) duty is (determined) by the command of a true teacher [i.e., sadguru-ājñā] and he should beg from (the Yoginīs and Mothers). O Kauleśa, he is successful by maintaining this attitude. [...]”.

Shakta (शाक्त, śākta) or Shaktism (śāktism) represents a tradition of Hinduism where the Goddess (Devi) is revered and worshipped. Shakta literature includes a range of scriptures, including various Agamas and Tantras, although its roots may be traced back to the Vedas.
Yoga (school of philosophy)
Source: ORA: Amanaska (king of all yogas): A Critical Edition and Annotated Translation by Jason BirchSadguru (सद्गुरु) refers to a “true Guru”, according to the Haṭhapradīpikā of Svātmārāma: an influential 15th-century Sanskrit manual on Hatha-Yoga dealing with techniques to channel one’s vital energy.—Accordingly, “Giving up sense objects is difficult to achieve; seeing the highest reality is [also] difficult, and [so too] is attaining the natural state [of Samādhi], without the compassion of a true Guru (sadguru)”.

Yoga is originally considered a branch of Hindu philosophy (astika), but both ancient and modern Yoga combine the physical, mental and spiritual. Yoga teaches various physical techniques also known as āsanas (postures), used for various purposes (eg., meditation, contemplation, relaxation).
In Buddhism
Tibetan Buddhism (Vajrayana or tantric Buddhism)
Source: OSU Press: Cakrasamvara SamadhiSadguru (सद्गुरु) refers to the “(sacred) true Guru”, according to the Guru Mandala Worship (maṇḍalārcana) ritual often performed in combination with the Cakrasaṃvara Samādhi, which refers to the primary pūjā and sādhanā practice of Newah Mahāyāna-Vajrayāna Buddhists in Nepal.—Accordingly, “Oṃ Āḥ Hūṃ to the highest beautiful feet of the sacred true Guru (sadguru), To the maker of right knowledge becoming manifest, homage Hūṃ”.

Tibetan Buddhism includes schools such as Nyingma, Kadampa, Kagyu and Gelug. Their primary canon of literature is divided in two broad categories: The Kangyur, which consists of Buddha’s words, and the Tengyur, which includes commentaries from various sources. Esotericism and tantra techniques (vajrayāna) are collected indepently.
Languages of India and abroad
Marathi-English dictionary
Source: DDSA: The Molesworth Marathi and English Dictionarysadguru (सद्गुरु).—m (S) A good Guru or spiritual instructor and director.
Marathi is an Indo-European language having over 70 million native speakers people in (predominantly) Maharashtra India. Marathi, like many other Indo-Aryan languages, evolved from early forms of Prakrit, which itself is a subset of Sanskrit, one of the most ancient languages of the world.
Sanskrit dictionary
Source: Cologne Digital Sanskrit Dictionaries: Cappeller Sanskrit-English DictionarySadguru (सद्गुरु).—[masculine] a good teacher.
Source: Cologne Digital Sanskrit Dictionaries: Monier-Williams Sanskrit-English DictionarySadguru (सद्गुरु):—[=sad-guru] [from sad > sat] m. a good teacher, [Kāvya literature; Bhāgavata-purāṇa; Siṃhāsana-dvātriṃśikā or vikramāditya-caritra, jaina recension]
Source: DDSA: Paia-sadda-mahannavo; a comprehensive Prakrit Hindi dictionary (S)Ṣaḍguru (षड्गुरु) in the Sanskrit language is related to the Prakrit word: Chaggaru.
[Sanskrit to German]
Sanskrit, also spelled संस्कृतम् (saṃskṛtam), is an ancient language of India commonly seen as the grandmother of the Indo-European language family (even English!). Closely allied with Prakrit and Pali, Sanskrit is more exhaustive in both grammar and terms and has the most extensive collection of literature in the world, greatly surpassing its sister-languages Greek and Latin.
Kannada-English dictionary
Source: Alar: Kannada-English corpusSadguru (ಸದ್ಗುರು):—[noun] a good teacher.
Kannada is a Dravidian language (as opposed to the Indo-European language family) mainly spoken in the southwestern region of India.
See also (Relevant definitions)
Starts with: Sadgurunatha, Sadgurustotra, Shadgurubhashya, Shadgurushishya.
Full-text: Sabji, Chaggaru, Saduguru, Jnanaghana, Hamsatma, True guru, Satsamgati, Satkarman, Ishtadevata, Sat, Thikana.
Relevant text
Search found 14 books and stories containing Sadguru, Sad-guru, Shadguru, Ṣaḍguru; (plurals include: Sadgurus, gurus, Shadgurus, Ṣaḍgurus). You can also click to the full overview containing English textual excerpts. Below are direct links for the most relevant articles:
Kena upanishad (Madhva commentary) (by Srisa Chandra Vasu)
Mantra 2.5 < [Book 2 - Dvitīya-Khaṇḍa]
Vivekachudamani (by Shankara)
Dvisahasri of Tembesvami (Summary and Study) (by Upadhyay Mihirkumar Sudhirbhai)
Brihad Bhagavatamrita (commentary) (by Śrī Śrīmad Bhaktivedānta Nārāyana Gosvāmī Mahārāja)
Verse 2.3.113 < [Chapter 3 - Bhajana (loving service)]
Verse 2.1.121 < [Chapter 1 - Vairāgya (renunciation)]
Verse 2.2.57 < [Chapter 2 - Jñāna (knowledge)]
Yogadrstisamuccaya of Haribhadra Suri (Study) (by Riddhi J. Shah)
Chapter 5.2 - Vedyasaṃvedyapada and Avedyasaṃvedyapada < [Chapter 5 - A Line of Demarcation between the first four and last four Yogadṛṣṭis]
Bhajana-Rahasya (by Srila Bhaktivinoda Thakura Mahasaya)
Text 13 < [Chapter 2 - Dvitīya-yāma-sādhana (Prātaḥ-kālīya-bhajana)]