What is Vocabulary?

Vocabulary (from the Latin for "name," also called wordstock, lexicon, and lexis) refers to all the words in a language that are understood by a particular person or group of people. There are two main types of vocabulary : active and passive. An active vocabulary consists of the words we understand and use in everyday speaking and writing. Passive vocabulary is made up of words that we may recognize but don't generally use in the course of normal communication.

Exactly how many words are there in the English language? There's no real answer to that question. In order to reach a plausible total, there must be a consensus as to what constitutes actual vocabulary. 

Likewise, the sum of a person's vocabulary is more than just the total number of words he or she knows. It also takes into account what people have experienced, reflected on, and either incorporated or rejected. As a result, the measure of vocabulary is fluid rather than fixed.

David Wolman, a frequent writer on language, Contributing editor at Outside, and longtime contributor at Wired said "English, probably more so than any language on earth, has a stunningly bastard vocabulary,". He also estimates that between 80 and 90% of all the words in the Oxford English Dictionary are derived from other languages. "Old English, lest we forget," he points out, "was already an amalgam of Germanic tongues, Celtic, and Latin, with pinches of Scandinavian and Old French influence as well."

English Vocabulary by Region

- Canadian English Vocabulary: Canadian English vocabulary tends to be closer to American English than British. The languages of both American and British settlers remained intact for the most part when settlers came to Canada. Some language variations have resulted from contact with Canada's Aboriginal languages and with French settlers. While there are relatively few Canadian words for things that have other names in other dialects, there is enough differentiation to qualify Canadian English as a unique, identifiable dialect of North American English at the lexical level.

- British English and American English: These days, there are many more American words and expressions in British English than ever before. Although there is a two-way exchange, the directional flow of borrowing favors the route from American to Britain. As a result, speakers of British English generally tend to be familiar with more Americanisms than speakers of American English are of Britishisms.

- Australian English: "Australian English is set apart from other dialects thanks to its abundance of highly colloquial words and expressions. Regional colloquialisms in Australia often take the form of shortening a word, and then adding a suffix such as -ie or -o. For example, a "truckie" is a truck driver; a "milko" is a milkman; "Oz" is short for Australia, and an "Aussie" is an Australian.

https://www.thoughtco.com/vocabulary-definition-1692597