The two crossword solutions for the term 'allow to expire' are 'ELAPSE' and 'letdie'. ELAPSE is defined as passing slowly or gradually, while letdie means to allow something to die out or come to an end. Both terms refer to the concept of allowing something to expire, which means to let it come to an end or pass away. This could refer to a period of time, a contract, or any other situation in which something is allowed to reach its natural conclusion.