IPA: /ˈsʌb.təl.ti/
KK: /ˈsʌbtlti/
A quality or state that is not obvious and is often difficult to notice, especially in thoughts or details.
The subtlety of her argument made it more convincing.
Subtlety is formed from "subtilis" (meaning fine or delicate) and the suffix "-ty" (indicating a state or condition). The word refers to the state of being fine or delicate, often in a nuanced or understated way.
Think of something that is 'fine' or 'delicate' — that's what subtlety means, the quality of being understated or nuanced.