1. A partial payment of a debt or purchase price, made at regular intervals until the full amount is paid.
Usage: Usually plural; British spelling (American: installments); Common in finance and retail contexts
2. One of several parts of a serialized story, book, or broadcast released over time.
Usage: Common in publishing and entertainment

Examples

• She bought the car on instalments, paying £300 each month for three years.
• The furniture store offers a payment plan with no interest if you pay in twelve equal instalments.
• The final instalment of the book series was released last week.
• He missed an instalment on his loan and faced a penalty fee.
• The TV drama aired in weekly instalments throughout the season.
• By paying in instalments, customers can afford expensive items more easily.