Unlike thimble, the words thumb, numb, and dumb have unetymological mb in spelling, though they do not end in l.

与thimble不同， thumb, numb, 和dumb这几个词在拼写上有非词源性的mb，虽然他们不以 l 结尾。

youdao

Brown continues to be listed with a "sprained right thumb" on L. A. 's injury report, but is not expected to miss any time.

布朗仍然以“拇指拉伤”呆在伤病名单，但是他不希望缺席任何比赛。

youdao

The general rule of thumb: If insomnia lasts a month and doesn't get better, talk to your doctor, says Frisca L. Yan-Go, M.

CNN: When to take a sleeping pill