An affix is an addition to a base form of a word in order to modify the meaning. An example is non in nonsense. Prefixes and suffixes are types of affixes.

An antonym is a word opposite in meaning to another word. Hot and cold are antonyms.

A base word, or root word, is the basic word to which affixes can be added. For example, to the base word manage, we can add -un and -able to form unmanageable.

A collocation is the placing together of two or more words in a common pattern. An example is the phrase wide awake.

A compound noun is a noun formed from two parts. An example is toothpaste, from the words tooth and paste. Another example is dry-cleaning, from the words dry and cleaning. A compound noun may be two separate words. An example is swimming pool.

A compound adjective is an adjective formed from two words. An example is good-looking.

A compound verb is a verb with two parts. It may be a single word formed from two distinct words, such as kickstart. It could be formed from to separate verbs, such as go shopping. It could also refer to two verbs connected to a single noun, such as the highlighted words in this sentence: The unhappy child moaned and groaned.

A false friend is a word that a language learner mistakenly thinks they recognise from their first language. For example, the Spanish verb contestar seems like it would mean to contest in English, but it actually means to answer.

Homonyms are words that share the same spelling and pronunciation, but have different meanings. An example is the word branch used to mean a part of a tree and also used to mean an outlet of a shop.

Homophones are words that share the same pronunciation but have different meanings. Examples are to and too or pain and pane.

An idiom is a word or phrase used with a figurative rather than a literal meaning. An example is when we say it is raining cats and dogs. Another example is when we call a person nuts (crazy).

A lexical set is a group of words with a similar form, meaning or purpose. An example of a lexical set is cat, dog and rabbit. (Pets) Another example is walked, listened, climbed and treated. These are all verbs that take the -ed ending in the past tense.

A phrasal verb is a multi-word verb that consists of a main verb plus a preposition (or adverb). Examples of phrasal verbs are take off, drop by and go on. Phrasal verbs can be made up of three words. An example is look up to.

A prefix is an addition to the beginning of a root word to form a new word. For example, en- can be added to the word large to make enlarge or to the word slave to make enslave.

The formality or informality of a piece of language.

A root word, or base word, is the basic word to which affixes can be added. For example, to the root word manage, we can add -un and -able to form unmanageable.

A suffix is an addition to the ending of a root word to form a new word. For example, -ful can be added to the word hope to make hopeful or to the word care to make careful.

A synonym is a word the same in meaning to another word. Big and large are synonyms.

A set of words based on the same root, such as act, action, active and react.