Hydrous oxide

Japanese: hydrous oxide（英語表記）hydrousoxide

...In a narrow sense, it refers to compounds with the general formula M(OH) _n ( n = 1, 2, 3, 4, etc.) that contain the hydroxide ion ^OH- as the anion. In a broad sense, it also includes hydrated oxides of metal ions, hydrous hydroxides, and amphoteric hydroxides that react not only with acids but also with alkalis (e.g., hydroxides of aluminum, tin, and arsenic Al(OH) ₃ _, Sn(OH) ₄ , As(OH) ₃ , etc.). Nonmetallic oxides that appear to contain hydroxyl groups from their composition but are actually acids (e.g., boric acid B(OH) ₃ = _B2O3 ･ _3H2O ) and certain metal oxides (e.g. _, chromic acid _CrO2 (OH) ₂ = _H2CrO4 = _CrO3 ･ _H2O ) are not called hydroxides. ...

*Some of the terminology that mentions "hydrous oxide" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…狭義には，陰イオンとしての水酸化物イオンhydroxide ion OH^－を含む，一般式M(OH)_n(n＝1,2,3,4など)であらわされる化合物を指す。広義には，金属イオンの水和酸化物hydrous oxide，水和水酸化物hydrous hydroxide，酸のみならずアルカリとも反応する両性水酸化物amphoteric hydroxide(たとえばアルミニウム，スズ，ヒ素の水酸化物Al(OH)₃,Sn(OH)₄,As(OH)₃など)も含まれる。組成からみれば水酸基を含むようにはみえるが，実際には酸である非金属酸化物(たとえばホウ酸B(OH)₃＝B₂O₃･3H₂O)や，ある種の金属酸化物(たとえばクロム酸CrO₂(OH)₂＝H₂CrO₄＝CrO₃･H₂O)などは水酸化物とは呼ばない。…