名詞 foible:

1. a behavioral attribute that is distinctive and peculiar to an individual
   同義詞：idiosyncrasy, mannerism
2. the weaker part of a sword's blade from the forte to the tip

1. My grandfather always carries his watch in his pocket; it's a foible of his.
   ＂我的祖父總是把手表放在口袋里，這是他的一種怪習(xí)性。＂
2. My grandfather always carries his watch in his pocket, it's a foible of his.
   我的祖父總是把手表放在口袋里，這是他的一種怪習(xí)性。

foi.ble

n.（名詞）
A minor weakness or failing of character.See Synonyms at fault
弱點，小缺點：性格上小的弱點或缺點參見 fault
The weaker section of a sword blade, from the middle to the tip.
劍刃：劍刃從中部到尖端的柔弱部分

來源：
Obsolete French foible [weak point of a sword, weak]
已廢法語 foible [劍的柔弱之處，軟弱的]
from Old French feble [weak] * see feeble
源自 古法語 feble [弱小的] *參見 feeble