Vocabulary

A vocabulary (also known as a lexicon) is a set of words, typically the set in a language or the set known to an individual. The word vocabulary originated from the Latin vocabulum, meaning "a word, name". It forms an essential component of language and communication, helping convey thoughts, ideas, emotions, and information. Vocabulary can be oral, written, or signed and can be categorized into two main types: active vocabulary (words one uses regularly) and passive vocabulary (words one recognizes but does not use often). An individual's vocabulary continually evolves through various methods, including direct instruction, independent reading, and natural language exposure, but it can also shrink due to forgetting, trauma, or disease. Furthermore, vocabulary is a significant focus of study across various disciplines, like linguistics, education, psychology, and artificial intelligence. Vocabulary is not limited to single words; it also encompasses multi-word units known as collocations, idioms, and other types of phraseology. Acquiring an adequate vocabulary is one of the largest challenges in learning a second language.

A vocabulary is the set of words in a given language that an individual knows and uses. In the context of linguistics, a vocabulary may refer more broadly to any set of words. Types of vocabularies have been further defined: a lexis is a vocabulary comprising all words used in a language or other linguistic context or in a person's lexical repertoire. An individual person's vocabulary includes a passive vocabulary of words they can recognize or understand, as well as an active vocabulary of words they regularly use in speech and writing. In semiotics, vocabulary refers to the complete set of symbols and signs in a sign system or a text, extending the definition beyond purely verbal communication to encompass other forms of symbolic communication.

Vocabulary acquisition is a central aspect of language education, as it directly impacts reading comprehension, expressive and receptive language skills, and academic achievement. Vocabulary is examined in psychology as a measure of language processing and cognitive development. It can serve as an indicator of intellectual ability or cognitive status, with vocabulary tests often forming part of intelligence and neuropsychological assessments.

Word has a variety of meanings, and our understand of ideas such as vocabulary size differ depending on the definition used.

The most common definition equates words with lemmas (the inflected or dictionary form; this includes walk, but not walks, walked or walking). Most of the time lemmas do not include proper nouns (names of people, places, companies, etc.). Another definition often used in research of vocabulary size is that of word family. These are all the words that can be derived from a ground word (e.g., the words effortless, effortlessly, effortful, effortfully are all part of the word family effort). Estimates of vocabulary size range from as high as 200 thousand to as low as 10 thousand, depending on the definition used.

The first major change distinction that must be made when evaluating word knowledge is whether the knowledge is productive (also called achieve or active) or receptive (also called receive or passive); even within those opposing categories, there is often no clear distinction. Words that are generally understood when heard or read or seen constitute a person's receptive vocabulary. These words may range from well known to barely known (see degree of knowledge below). A person's receptive vocabulary is usually the larger of the two. For example, although a young child may not yet be able to speak, write, or sign, they may be able to follow simple commands and appear to understand a good portion of the language to which they are exposed. In this case, the child's receptive vocabulary is likely tens, if not hundreds of words, but their active vocabulary is zero. When that child learns to speak or sign, however, the child's active vocabulary begins to increase. It is also possible for the productive vocabulary to be larger than the receptive vocabulary, for example in a second-language learner who has learned words through study rather than exposure, and can produce them, but has difficulty recognizing them in conversation.

Productive vocabulary, therefore, generally refers to words that can be produced within an appropriate context and match the intended meaning of the speaker or signer. As with receptive vocabulary, however, there are many degrees at which a particular word may be considered part of an active vocabulary. Knowing how to pronounce, sign, or write a word does not necessarily mean that the word that has been used correctly or accurately reflects the intended message; but it does reflect a minimal amount of productive knowledge.

Within the receptive–productive distinction lies a range of abilities that are often referred to as degree of knowledge. This simply indicates that a word gradually enters a person's vocabulary over a period of time as more aspects of word knowledge are learnt. Roughly, these stages could be described as: