Transactional language is language which is used to make a transaction and which has a result. It can be compared with interactional language, which is used to maintain relationships.
Learners in exams are often required to write a transactional letter, which has a clear objective, e.g. asking for a refund or for information, or making a complaint.
In the classroom
Transactional language is often taught more than interactional language, as it involves shorter turns, simpler and more predictable language, and can have a measurable result.