The crossword solution for the term 'Word with 'BIRTH' or 'INTEREST' is RATE, which is a four-letter word. RATE is a verb that means to estimate the value, quality, or extent of something. It can also mean to assign a standard or value to something. RATE is often used in the context of BIRTH RATE, which is the number of live births per 1000 people in a population, and INTEREST RATE, which is the amount charged by a lender to a borrower for the use of money.