1. Lexicology as a branch of linguistics. Lexical units

17. Regional varieties of the English language. Lexical differences.
British English (BrE) is the form of E used in the UK. It includes all E dialects used within the UK. Dialects: English English (Southern E, Midlands E, Northern E dialects), Welsh E Scottish E).
Received pronunciation (RP) – is the form of E, spoken mostly by educated speakers. It derives from a mixture of the Midland and Southern dialects which were spoken in London during the Middle Ages and is used as a model for teaching E to foreign learners.
One of the best known Southern dialects is Cockney, the regional dialect of London. It exists in 2 levels:
spoken by the educated lower middle classes;
spoken by the uneducated; differ from Southern E in pronunciation, vocabulary, morphology and syntax.
AmE is the form of E used in the USA. AmE cannot be called a dialect as it is a regional variety. Because it has a literary normalized form called Standard American (a dialect has no literary form). But it not a separate lg because it has neither grammar nor vocabulary of its own.
A number of E idioms that have essentially the same meaning show lexical differences between the Br and Am version of E. For ex: Br ---- Am:
skeleton in the cupboard – sk in the closet;
storm in a teacup – tempest in a tea pot;
a cinema – a movies
one room – apartment
pavement – sidewalk
The first Am dictionary was published by Noah Webster in 1806. Americans tended to simplify the spelling.
Ex: ce → se: defense, offense;
re → er: center, theater;
our → or: honor, favor.
traveler (one l)
delition of unpronounced endings: program, tho, thro.

18. Ways of enriching and expanding the English lexicon.
As has been already mentioned, no vocabulary of any living language is ever stable but is constantly changing, growing and decaying. The changes occurring in the vocabulary are due both to linguistic and non-linguistic causes, but in most cases to the combination of both. Words may drop out altogether as a result of the disappearance of the actual objects they denote some words were ousted¹ as a result of the influence of Scandinavian and French borrowings Sometimes words do not actually drop out but become obsolete, sinking to the level of vocabulary units used in narrow, specialised fields of human intercourse making a group of archaisms: e g.