It is important to make a distinction between
Vocabulary is traditionally understood as a stock of individual words with fixed meanings.
Lexis includes not only the single words but also the word combinations that we store in our mental lexicons.
Readers need to know at least 90% of the words in a text to achieve comprehension so it is essential that language learning and teaching consider that learners must understand from their linguistic experience and employing strategies to make sense of the passage accordingly to the purpose of reading or listening.
Taxonomy of lexical items:
• words book, pen
• polywords by the way, upside down
• collocations, or word partnerships community service, absolutely convinced
• institutionalized utterances I’ll get it; We’ll see; That’ll do; If I were you . . .; Would you like a cup of coffee?
• sentence frames and heads That is not as . . . as you think; The fact/suggestion/problem/danger was . . .
• text frames In this paper we explore . . .; Firstly . . .; Secondly . . .; Finally . . .
Lewis (1997b)A vocabulary is a set of familiar words within a person's language. A vocabulary, usually developed with age, serves as a useful and fundamental tool for communication and acquiring knowledge. Acquiring an extensive vocabulary is one of the largest challenges in learning a second language.
WikipediaTED Talk
Go ahead, make up new words! 6:44
Many people who learn English think that words are like scientific facts, and they don't change. But the word is just an agreement between people who use the language. If many people agree on the meaning of a word in a language, then it becomes part of the vocabulary. People who learn English often feel that they must abide by the rules of language, or they would seem to have committed embarrassing sins.