Morphemic structure of English words.
The morpheme is the smallest meaningful unit of form. Morphemes occur in speech only as constituent parts of words, not independently, although a word may consist of single morpheme.
Words reveals that they are composed of morphemes of different types: root-morphemes and affixational morphemes.
The root-morpheme is the lexical nucleus of a ward, it has an individual lexical meaning shared by no other morpheme of the language. Besides it may also possess all other types of meaning proper to morphemes except the part-of-speech meaning which is not found in roots. The root-morpheme is isolated as the morpheme common to a set of words making up a word-cluster, for example the morpheme teach-in to teach, teacher, teaching.
Affixational morphemes modify the meaning of the root morpheme. They are lexically always dependent on the root which they modify. They possess the same types of meaning as found in roots, but unlike root-morphemes most of them have the part-of-speech meaning which makes them structurally the important part of the word as they condition the lexico-grammatical class the word belongs to.
Are classified into affixes building different parts of speech: nouns, verbs, adjectives or adverbs.

Free morphemes coincide with word-forms of independently functioning words. It is obvious that free morphemes can be found only among roots, so the morpheme boy- in the word boy is a free morpheme; in the word undesirable there is only one free morpheme desire-; the word pen-holder has two free morphemes pen- and hold-.
Bound morphemes are those that do not coincide with separate word-forms, consequently all derivational morphemes, such as -ness, -able, -er are bound. Root-morphemes may be both free and bound. The morphemes theor- in the words theory, theoretical, or horr- in the words horror, horrible, horrify are bound roots as there are no identical word-forms.
Semi-bound morphemes are those that can function both as an affix and a free-morpheme. E.g. well: sleep well, well-known; half: half an hour, half-done

A morpheme is a segment of a word regularly recurrent in other words and having the same meaning in all of its recurrences. The word has both lexical and grammatical meaning while the morpheme — only lexical. In some morphemes (like suffixes) the connotational (emotive charge) component can prevail (deminutive).
Some morphemes have the part-of-speech meaning.
Also morphemes have differential and distributional meanings.
Differential meaning serves to distinguish one word from all other words containing the same morphemes (precook, overcook).
Distributional meaning — is the meaning of the order and arrangement of morpheme making up words.

The morphemic structure of the word is being established by the method of immediate and ultimate constituents (непосредственных и конечных составляющих). This method is based on a binary principle which means that at each stage the word is broken into the components (immediate constituents) after that these components are broken further into two other components. When the components can't be further divided and the analysis is completed we have arrived at the ultimate constituents — the morphemic structure of the word.
Friend-ly-ness

Morphemes can be
Monomorphic (with one root) and
Polymorphic (more than one root) - eyeball