The phrase "in every nook and cranny" means that something has been thoroughly searched or explored, leaving no area untouched. Some synonyms for this phrase include "high and low," "far and wide," "from top to bottom," and "inside and out." These phrases emphasize the effort and thoroughness put into a search or exploration. Other synonyms include "everywhere," "all over," and "throughout," which emphasize the extent and coverage of the search or exploration. The phrase can be used to describe physical spaces, such as a house or room, as well as abstract concepts, like research or investigation.