词根:grat (grac) = thankful, pleasing(喜好)

  词根grat来自拉丁语的grat意为thankful,pleasing 等。grac是它的变形。
   (*拉丁文gratus(=pleasing),gratia(=favour)——英文字根字典)

同源词:

1. gratuitous adj.免费的,无报酬的;没有理由的(作为感谢而做的grat(=thank,pleasing))
  gratuity n. 遗散费;(军人的)退役金
  Your gratuitous cruelty is abominable.I've had enough!你那无端的残忍在令人生厌,我已经受够了!

2. ingratiate vt.(~oneself)使满意,讨好,迎合 (使对方感到好感in(=in) + grat (=thank,pleasing,favor))
  Despite my lack of credentials,I ingratiated myself with the hiring manager.虽然我不够资格,但我逢迎了招聘主管,使其对我满意。

3. congratulate v.祝贺 *con<com(=together)
  congratulatory adj.祝贺的 congratulatory letter/telegram 贺信/贺电

4. congratulation n.祝贺;庆贺;(pl.)祝词 *con<com (=together)
  Congratulations !祝贺;offer one's congratulations to 对...说祝贺的话

5. ungrateful adj.忘恩负义的,不知感谢的 *un (=not)

6. grateful adj.感谢的,感激的;令人高兴的,令人愉快的
  I am grateful to you for your kindness.谢谢你的好意。
  grateful letter 感谢信;trees that afford a grateful shade 有宜人荫凉的大树

7. gratis adv./adj.免费地(的)
  be admitted gratis 免费入场

8. gratitude n.感谢,谢意
  in token of my gratitude 为表达我们的一片谢意

9. grace n.优雅;好意,恩惠;(饭前、饭后的)谢恩祈祷;(神的)恩宠;慈悲;阁下,阁下夫人;(票据等的)宽限期
        v.使优雅;使增光
  graceful adj.优雅的 graceful dancer 优雅的舞蹈家;graceless难看的;粗俗的,不知礼的;graceless behavior 粗俗的行为;gracious 亲切的;慈悲的;her gracious Majesty the Queen 女王陛下

10. disgrace n.丢脸,耻辱;失宠
            v.使丢脸,玷污;使失宠 *dis(=not)
  disgraceful 可耻的;disgraceful behavior可耻的行为

11. ingrate n.忘恩负义的人 (in- = not)
   ingratitude n.忘恩负义

12. ingratiate v.讨好;逢迎(使高兴向着某人)《in- = toward》
   ingratiation n.讨好;巴结