A constrainer is often associated with words like restrictor, limiter, or inhibitor. These terms all refer to something that is limiting or hindering in some way. For example, a restrictor might put a cap on the amount of something that can be consumed, while an inhibitor might prevent a process from moving forward. Synonyms for constrainer might also include terms like suppressor or controller, which suggest a sense of control being exerted over a situation. Whatever the specific word used, the idea behind it is to describe something that is impeding progress or limiting possibilities.