noun
monetary reward; honorarium; gratuity
Refers to money given as a token of gratitude, often for a service or favor, such as a speaker's fee or a thank-you payment.
講演の謝金を受け取る。
Receive an honorarium for the lecture.
お世話になった医師に謝金を包んだ。
I gave a monetary thank-you to the doctor who took care of me.
報酬 is a broader term for compensation or remuneration for work, while 謝金 specifically emphasizes gratitude and is often a one-time payment for a favor or service.
謝礼 is a near-synonym also meaning a reward or thank-you gift, but 謝金 explicitly refers to money, whereas 謝礼 can include non-monetary gifts.
Compound of 謝 (しゃ, 'thanks, apology') and 金 (きん, 'money'). The combination straightforwardly means 'thank-you money'.