Lexis meaning ‘word, phrase’ (hence lexicos ‘having to do with words’) and logos

Derivational patterns.
A derivational pattern is a regular meaningful arrangement of immediate constituents in the derived word, a structure that imposes rigid rules on the order and the nature of the derivational bases and affixes that may be brought together.
Patterns of derivative structures are usually represented in a generalised way in terms of conventional symbols: small letters v, n, a, d, пит
DPs may represent derivative structure at different levels of generalisation:

1. 
   at the level of structural types specifying only the class membership of ICs and the direction of motivation, such as a+-sf -> N, prf- + n -> V, prf- n -> N, n + -sf -> N, n + -sf -> V, etc.
   

In terms of patterns of this type, known as structural formulas, all words may be classified into four classes:
1. suffixal derivatives, e.g. friendship, glorified, blackness, skyward
2. prefixal derivatives, e.g. rewrite, exboxer, non-smoker, un-happy
3.conversions, e.g. a cut, to parrot, to winter
4.compound words key-ring, music-lover, wind-driven.
But derivational formulas are not indicative either of any one lexical-grammatical or lexical class of words, as, for example, the formula a + -sf may equally represent suffixal nouns as in blackness, possibility and verbs, as in sharpen, widen, or adjectives as in blackish.

2. 
   derivative structure and hence derivative types of words may be represented at the level of structural patterns which specify the base classes and individual affixes thus indicating the lexical-grammatical and lexical classes of derivatives within certain structural classes of words. The suffixes refer derivatives to specific parts of speech and lexical subsets as, for example, v + -er -> N signals that the derivatives built on this pattern are de-verbal nouns which represent a semantic set of active agents, denoting both animate and inanimate objects, e.g. reader, runner, singer, unlike, for example, denominal nouns with the underlying pattern п+ -еr -> N which stands for agents denoting residents or occupations, e.g. Londoner, villager, gardener. The DP n+-ish -> A signals a set of adjectives with the lexical meaning of resemblance, whereas a + -ish -> A signals adjectives meaning a small degree of quality.
   

c) DPs may be specified as to the lexical-semantic features of both ICs. DPs of this level specify the semantic constraints imposed upon the set of derivatives for which the pattern is true and hence the semantic range of the pattern. For example, the nominal bases in the pattern n+-ess -> N are confined to nouns having in their semantic structures a component ‘a female animate being’, e.g. lioness, traitress, stewardess, etc.; the nominal bases in n+-ful -> N are limited by nouns having a semantic component ‘container’, e.g. lungful, carful, mouthful, whereas in n+ -ful -> A the nominal bases are confined to nouns of abstract meaning.
It follows that derivational patterns may be classified into two types — structural pattern (see b, above) and structural-semantic pattern (see c).
6) The three main sources of enriching vocabulary.