serve
To help people or provide something useful to them.
To serve means to help or provide something useful to others. When you serve your community, you might volunteer at a food bank or help elderly neighbors with yard work. A waiter serves food to restaurant customers. A doctor serves patients by treating their illnesses.
The word carries a sense of usefulness and purpose. When something serves a function, it fulfills a useful role: a bookmark serves to hold your place in a book. A sturdy rope can serve as a swing. Teachers serve their students by helping them learn and grow.
In sports, serve has a specific meaning: to start play by hitting or throwing the ball. In tennis, you serve by tossing the ball up and hitting it across the net. In volleyball, you serve by hitting the ball over the net to the other team.
The word also appears in phrases like “first come, first served,” meaning whoever arrives earliest gets helped first. A prison sentence might be called serving time. When you serve someone right, it means they're getting exactly what they deserve: “She studied hard all semester while he played video games, so it serves him right that she got the lower grade.”