(mineralogy) The nonahydrate of iron(III) sulfate.

(arithmetic, uncountable) The process of subtracting a number from another. / (arithmetic, countable) A calculation involving subtracting. / The removal of something.

(anarchism) The theories of Murray Bookchin (1921–2006), American anarchist and political theorist, known for his work on social ecology.

(zoology) One of the radial segments making up the body of one of the Coelenterata or similar organism