Collocations are words that are often used together, such as utterly fascinating or concerted effort. They can be difficult to learn because they are not always predictable, and a collocate for one word does not always work as a collocate for a near synonym of that word. For example, we don't say utterly interesting, nor do we say hard effort or voice a worry.

Collocation is a central feature of language and being able to produce natural word combinations is an indication of fluency. Collocation also contributes to meaning. Most common words have more than one meaning, and we use the surrounding context to indicate which meaning is intended. Collocation plays a big part in this process.

The Macmillan Collocations Dictionary was created to help upper intermediate to advanced learners of English write more natural and idiomatic English.

Key features of the Collocations Dictionary include the following:

- Collocations are presented for over 4,500 carefully selected key words
- The content focuses on language learners' productive needs
- Within each entry, collocations are grouped in semantic sets
- Special focus is placed on collocations that are frequent in academic and professional writing
- The content incorporates examples for each semantic set to show how collocations are used in context
- Extra usage boxes are shown with grammatical notes, synonyms and alternative expressions that are frequently used