communicative competence: the general ability to use language accurately, appropriately and flexibly
grammatical competence: the ability to use words and structures accurately as part of communicative competence
sociolinguistic competence: the ability to use language appropriately according to the social context as part of communicative competence
strategic competence: the ability to use language to organize effective messages and to overcome potential communication problems as part of communicative competence
communication strategy: a way of overcoming a gap between communicative intent and a limited ability to express that intent, as part of strategic competence