| Term | Definition |
| agenda feedback | predictive pre-picked error correction |
| interlanguage | a learner's language at a point of development between the system of the native language and the target language (Selinker 1972) |
| intralingual error | error that come from the development of interlanguage, such as 'overgeneralisation' of rules. The cognitivist view of the sources of error. |
| interlingual error | error due to L1 interference. According to the Contrastive Analysis Hypothesis this accounts for all errors |
| pre-systematic error | error made because the learner does not yet know the rule |
| systematic error | error made when the learner knows, or partly knows, the rule. It can usually be self-corrected if prompted |
| post-systematic error | 'a mistake' made when the interlanguage system is mastered. It can be self-corrected without prompting |
| mistake | error due to a slip or random guess, as often made by native speakers - i.e. a performance error. The rule is known but not applied. |
| error | manifestation of the state of the learner's interlanguage reflecting the competence of the learner |
| global error | error that causes confusion of the intended message or meaning |
| local error | error that doesn't interfere with the intended meaning and is easily recognised |
| fossilization | metaphor for relatively permanent errors in otherwise competent learners. It may not be irreversible, but the learner may be resistant to doing so |
| cognitive feedback | feedback on the information received by the listener, typically conveyed linguistically |
| affective feedback | feedback which shows the attitude of the listener and is given through 'kinesic mechanisms' - gesture, voice, facial expressions |