Mahesvara (English spelling)

Japanese: Maheśvara（英語表記）Mahesvara

…He is the chief deity of Hinduism, along with Vishnu and Brahma. He is identified with Rudra in the Rig Veda, and is also known by other names such as Hara, Śaṃkara, Mahādeva (the Great God), and Maheshvara (the Great God). He also drank a deadly poison that threatened to destroy the world during the ancient Churning of the Ocean of Milk in order to save the world, and because of his blue-black neck, he is called Nilakaṇṭha (the Blue Neck). …

From [Daijizaiten]

…The translation of Sanskrit Mahesvara (Mageishiyuraten). The supreme deity of Hinduism, Shiva, was adopted into Buddhism and became a guardian deity.

*Some of the terminology explanations that mention "Maheśvara" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…ビシュヌやブラフマー(梵天)と並ぶヒンドゥー教の主神。《リグ･ベーダ》のルドラと同一視され，ハラHara，シャンカラŚaṃkara，マハーデーバMahādeva(大天)，マヘーシュバラMaheśvara(大自在天)などの別名を有する。彼はまた世界を救うために，太古の〈乳海攪拌〉の際に世界を帰滅させようとする猛毒を飲み，青黒い頸をしているので，ニーラカンタNīlakaṇṭha(青頸（しようきよう）)と呼ばれる。…