按揭 refers to a mortgage, specifically a long-term housing loan repaid in installments. As a verb, it means 'to take out a mortgage' or 'to purchase with a mortgage', and is often used in patterns like 按揭买房 (buy a house with a mortgage) or 按揭贷款 (mortgage loan). Be aware that the English word 'mortgage' can also translate to 抵押 (dǐyā), which is a broader term for any pledge or secured loan; 按揭 is specialized for property installment loans.