There are several synonyms for the phrase "allow to borrow." One common alternative is "lend," which refers to the act of giving someone permission to use a particular item or sum of money for a specific period of time. Another possible synonym is "loan," which also pertains to providing someone with temporary access to a particular resource with the intention of being repaid in the future. Other related words might include "let," "grant," "authorize," or "permit," all of which connote giving someone permission or providing them with a provisional benefit. In any case, the essential concept behind these terms is the act of allowing someone to use something which belongs to someone else for a specified period.