1. (verb) to be expert, proficient, adept.
Nō waenganui o te tekau tau atu i 1920, i reira tonu a ia e tohunga ana, e noho kaitiaki ana (TTR 1996:159). / In the mid 1920s he was still active there as a tohunga and guardian.
2. (noun) skilled person, chosen expert, priest, healer - a person chosen by the agent of an atua and the tribe as a leader in a particular field because of signs indicating talent for a particular vocation. Those who functioned as priests were known as tohunga ahurewa. They mediated between the atua and the tribe, gave advice about economic activities, were experts in propitiating the atua with karakia and were experts in sacred lore, spiritual beliefs, traditions and genealogies of the tribe. Tohunga mākutu, or tohunga whaiwhaiā, specialised in the occult and casting evil spells. Those chosen to specialise in carving are tohunga whakairo, in tattooing are tohunga tā moko, in astrology are tohunga kōkōrangi, in composing songs are tohunga tito waiata, in canoe making are tohunga tārai waka, in rituals are tohunga karakia, etc. Tohunga were trained in a traditional whare wānanga or by another tohunga.
Ki te kore he kai, kua riro mā tētahi o ngā tohunga e karakia, kua rere mai he kai ki runga ki te waka. He ika, he manu me ētahi atu tūmomo kai mata (HP 1991:9). / If there was no food, one of the tohunga would say a ritual chant and food would fly onto the vessel - fish, birds and other types of raw food.
Me puta i a mātou tētahi kupu whakaatu mō ngā tohunga Māori o mua, mō ō mātou hoa Pākehā hoki kia mārama ai rātou ki te āhua o ērā tū tāngata. Arā, i te takiwā e mana ana ngā mahi mākutu he tino tangata te tangata tohunga i ngā kāinga Māori katoa atu, he tangata whai mana ia. He tangata ia e whakanuia ana, e manaakitia ana e te tangata katoa atu; ka kore i te aroha ki tōna tinana, he wehi pea ki tōna mana i pēnā ai. He atua ana kaimahi, arā ko ngā wairua o ētahi o ana tamariki kua mate atu, ōna whanaunga kē atu rānei, ā e rongo tonu ana aua atua ki āna tono. Ki te whakaaro a te tangata e whai mana ana aua atua ki te oneone, ki te rangi, ki te ahi, ki te wai, ki ngā tinana hoki me ngā tikanga katoa atu o te tangata. Nō konei ka pā he mate ki te tangata kia kīia tonutia he atua e ngau ana i a ia, he mea unga nā tētahi tangata mauāhara ki a ia. E kore e kimihia māriretia tōna take noa iho o te mate; engari ka kīia tonutia he atua kua uru ki te tinana o te tangata kua pāngia e te mate, ā e kore e taea te pei noa iho, me karakia anō e taea ai, kātahi ka tīkina te tohunga māna e mahi. Ehara i te mea he mahi whakaora anake te mahi a te tohunga, engari he kaha anō tōna ki te whakapā he mate ki te tangata, ki te mahi noa atu hoki i ētahi mahi whakamīharo nui, i runga i te kaha o ōna atua. Ka hiahia te tangata kia mate tōna hoariri, nā me tiki ia i tētahi wāhi o te kahu, tētahi o ngā huruhuru rānei o te māhunga, o taua tangata, tētahi mea noa atu rānei kua pā ki te tinana o taua tangata, arā o tōna hoariri, ka mutu ka mauria taua mea ki te tohunga hei whāngai hau; ā (ki te mea ka rahi he utu māna) ka karakiatia taua mea e te tohunga, kātahi ka werohia te tangata rā e ngā atua o te tohunga, ka nohoia rānei tōna tinana e aua atua, ka mate hoki ia, ka hemo rawa atu, arā ki te kore ia e kite i tētahi tohunga kaha rawa kia ripaia tōna mate; kātahi ka hoki mai ki te kai i a ia ngā atua o te tohunga nāna nei i mākutu te tangata e mate ana - he mea tāiro hoki (TWMNT 14/12/1875:294). / We must express a few words about the ancient Māori tohunga, and for our Pākehā friends so that they understand the nature of those kinds of people. At the time when witchcraft was prevailed, the tohunga was an important person in every Māori village. He was a person of prestige, was honoured and treated with consideration, if not for love of him as a person, then perhaps from fear of his power. His workers were atua, namely the spirits of some of his children who had died, or some near relations, and those atua heeded his requests. People considered that those atua had power over the earth, the heavens, fire, and water, as well as over the body and affairs of people. And so when a person became sick it was ascribed to an atua, instigated against him/her by someone bearing ill will. They would not search for any material cause of the disease; but would immediately attribute it to an atua, and it could not be ejected except by ritual chants, so then the tohunga were fetched to do his work. The tohunga could not only heal, but could also inflict diseases on someone, and perform amazing deeds through the power of his atua. When someone wanted to destroy his enemy, he needed to procure a portion of his garment, or a hair of his head, or something that had been in contact with that person's body, that is his enemy, and then take it to the tohunga to make ceremonial offering of food to the atua, and (provided the payment was sufficient) the tohunga would perform certain incantations over it. Then that person would be pierced by the tohunga's atua or his body would be invaded by the atua and he would become sick and die, that is unless he were able to procure the services of a more powerful tohunga to save him; in which case the tohunga's incantations would recoil upon himself, and he would probably become the victim.
(Te Māhuri Textbook (Ed. 2): 122-123;)