Composition is the way of word building when a word is formed by joining two or more stems to form one word. A sunbeam (a bright sunbeam)
Determinatum – a basic, determining, grammatically most important part (beam); it undergoes inflection: sunbeams.
Determinant –a determined part, serves to differentiate it from other beams (sun) - (H. Marchand).
The structural unity (integrity, indivisibility) of a compound word depends upon :
A) the unity of stress, (L. Bloomfield)
B) solid or hyphenated spelling,
C) semantic unity,
D) unity of morphological and syntactical functioning. (E.Nida)
These are characteristic features of compound words in all languages. For English compounds some of these factors are not very reliable.
1) As a rule English compounds have one uniting stress (usually on the first component), e.g. `hard-cover, ` best-seller.
2) A double stress in an English compound, with the main stress on the first component and with a secondary stress on the second component, e.g. `blood-`vessel.
3)The third pattern(N+A) is: two level stresses, e.g. `snow-`white, `sky-`blue.
The third pattern is easily mixed up with word-groups unless they have solid or hyphenated spelling.