Word-Composition or compounding is one ofthe productive ways of word-building when a new word is formed by joining twoor more stems. Compound words are inseparable vocabulary units that arestructurally and semantically based on the relationship between theircomponents through which they are motivated.

The structural unity of a compound worddepends upon:

•       The unity of stress where compounds have three stress patterns: a) a high or unitingstress on the first component, e.g.̀hardcover, ̀best-seller, ̀catnap, ̀doorway, b) a double stress with themain stress on the first component and with a secondary stress on the secondcomponent, e.g. blood-vessel, ̀ ̀washing-machine, c) the third patternof stresses is two level stresses, e.g. snow-̀̀white, ̀sky-̀blue, ̀arm-̀chair.

•       Solid or hyphenatedspelling. Generally many compound words havetwo types of spelling: written either solidly or with a hyphen, e.g. heartbreak, keyhole, highway, bookshop,father-in-law, parttime, baby-sitter, bank-manager. But some compounds arewritten separately – shock wave, terracedhouse.

•       The semantic unity of a compound word is often very strong. In such cases we haveidiomatic compounds where the meaning of the whole is not a sum of meanings ofits components, e.g. to ghostwrite,skinhead, brain-drain. In non idiomatic compounds semantic unity is notstrong, e.g., airbus, to download,astrodynamics etc.

•       Unity of morphological andsyntactical functioning are used in a sentenceas one part of it and only one component changes grammatically, e.g. These girls are chatter-boxes. «Chatter-boxes»is a predicative in the sentence and only the second component grammaticallychanges.

There are two characteristic features ofEnglish compounds:

•       both components in Englishcompounds are free stems, that is they can be used as words with a distinctivemeaning of their own. The sound pattern will be the same except for thestresses, e.g. a greenhouse and a green house.

•       English compounds have atwo-stem pattern, with the exception of compound words which have form-wordstems in their structure, e.g. middle-of-the-road(adj.) off-the-record, up-and-doing,up-and-coming (adj.), down-and-out(n.) etc.

 Thetwo-stem pattern distinguishes English compounds from German ones.