koostissõna

Koostissõna is an Estonian term that refers to a compound word. In Estonian linguistics, compound words are formed by combining two or more existing words to create a new word with a distinct meaning. These new words often express a concept more concisely or specifically than a phrase would.

The formation of koostissõna can occur in several ways, primarily through the joining of a noun with another noun, a noun with an adjective, or a verb stem with a noun. The primary component typically determines the grammatical category of the new word, and the secondary component modifies or specifies its meaning. For example, "päikesekell" (sundial) is formed from "päike" (sun) and "kell" (clock), where "päike" specifies the type of "kell."

Koostissõna are a common feature of the Estonian language and contribute to its rich vocabulary. They are used across all registers of language, from everyday conversation to specialized terminology. Understanding how these words are constructed is key to comprehending Estonian grammar and word-formation processes. The meaning of a koostissõna is usually derivable from the meanings of its constituent parts, though some compounds may develop idiomatic meanings over time.