noun / verb
tip
TIP/tɪp/
An extra payment for service, or to give such a payment.
The customer gives the waiter a tip after paying for the meal.

Etymology
The earlier verb meant “give, hand, pass” in thieves’ cant. It narrowed to giving a small monetary present for service, and the noun names that payment; the verb’s deeper origin is uncertain.
In context
meant to cover the cost of service and is usually paid directly to the restaurant, not just the server. Because it is a mandatory fee, it is different from a tip, which is optional