"At full stretch" is an idiomatic phrase used to describe someone or something reaching their maximum effort or capacity. However, there are several synonyms that can be used interchangeably to convey the same meaning. These synonyms include "at full capacity," "at maximum effort," "at full tilt," "to the fullest extent," and "reaching one's limit." Each of these phrases conveys the idea that someone or something is giving their all or can no longer push any harder. Whether it be physical, mental, or emotional exertion, these synonyms for "at full stretch" imply a high level of dedication and effort.