Co-text refers to the words surrounding a particular word or passage within a text that provide context and help determine meaning. For example, the words "door", "keyboard", and "the problem" provide co-text for the meaning of the word "key". Co-text refers to the linguistic environment of a word, while context refers to the non-verbal environment in which a word is used, such as images that could help explain the meaning of the word "goal". Understanding the co-text surrounding a word, such as verbs that commonly occur with "goal", can help English learners use that word properly.