There are several synonyms for the phrase "in safekeeping," which means to be under protection or care to prevent harm or loss. One of these synonyms is "secured," which suggests that something is being held in a safe and protected manner. Another synonym is "kept safe," which is a more straightforward way of indicating that something is being protected from harm or danger. "Under lock and key" is also a common phrase that can be used as a synonym for "in safekeeping," which implies that something is being kept under strict control and surveillance to ensure its safety. Other synonyms include "guarded," "protected," and "watched over".