aineittain

Aineittain is a Finnish adverb formed from the noun aine ("subject", "material" or "substance") and the distributive suffix -ittain. It is commonly used to indicate that something is organized, reported or considered separately for each subject, material or category — in other words "by subject" or "per subject".

Usage appears in both everyday and formal contexts. In education and administration, aineittain describes organization by school subjects (for example, opetusta järjestetään aineittain). In statistics and reporting, aineittain indicates breakdowns by category or field (tilastot aineittain). It can also appear in contexts relating to materials or ingredients, meaning separated by material type. Aineittain is closely related to synonyms such as ainekohtaisesti and aiheittain, and belongs to a productive class of Finnish adverbs formed with -ittain (for example kaupungeittain, viikoittain).

Grammatically, aineittain functions as an adverbial modifier and does not change form for number or case. Its meaning depends on the base noun: when combined with different nouns, the suffix conveys distribution or separation across the items denoted by that noun. The term is neutral and descriptive, used to clarify how data, activities or objects are grouped or presented.