A more thorough explanation:

An honorarium is a payment made to someone for their services, when fees cannot legally be paid or are not traditionally paid. It can also be a voluntary donation given in appreciation of services that cannot be compensated in money.

• A guest speaker at a conference may receive an honorarium for their presentation, as they are not an employee of the organization and cannot be paid a salary.
• A musician may receive an honorarium for performing at a charity event, as they are donating their time and talent for a good cause.
• In ancient Rome, honoraria were given to professionals, such as lawyers or doctors, as a voluntary payment for their services.

These examples illustrate how an honorarium is a payment or donation given in recognition of services that cannot be compensated in a traditional manner. It is often used in situations where payment of a fee is not possible or customary, such as for guest speakers or volunteers.