In modern linguistics it is more or less universally recognized that the smallest two-facet language unit possessing both sound-form and meaning is the morpheme. Unlike words morphemes do not possess grammatical meaning. Lexical meaning with its denotational and connotational components may be found in morphemes of different types: root-morphemes and affixal morphemes but there is a certain semantic difference between these types of morphemes.
Morphemes also posses specific meanings of their own. It is suggested that at least three more components of meaning may be observed in morphemes and namely: the differential, the functional and the distributional meaning. Differential meaning is the semantic component that serves to distinguish one word from all others containing identical morphemes. In words consisting of two or more morphemes, one of the constituent morphemes always has differential meaning: e.g. bookshelf, is different from bookcase, bookshop, and notebook from exercisebook, copybook. Functional meaning is the semantic component that serves primarily to refer the word to a certain part of speech. Functional meaning can be found in derivational morphemes only and lies astride the borderline between the lexical and the grammatical types of meaning.e.g.the meaning of -ment in movement, establishment,
Distributional meaning is the meaning of the order and arrangement of morphemes making up the word, cf. singer and ersing, boyish and ishboy, movement and mentmove. It can be found in all words containing more than one morpheme,
MEANING AND MOTIVATION
Motivation is understood as direct connection between the word structure and its meaning. If the connection between the structure and meaning is arbitrary and conventional, the words are described as non-motivated e.g. book, boy,cat, dog .
Morphological motivation implies a direct connection between the lexical meaning of the component morphemes, the pattern of their arrangement and the meaning of the word, e.g. teacher, rethink, dishwasher. The degree of morphological motivation may be different varying from the extreme of complete motivation to lack of motivation.
Phonetical motivation implies a direct connection between the phonetic structure of the word and its meaning, e.g.hiss, cuckoo, purr, splash, pooh, fie. Phonetical motivation is not universally recognized in modern linguistic science