微妙 (wēi miào): ละเอียดลึก

After they broke up, they still kept in touch; their relationship became very subtle—they were neither lovers nor ordinary friends.

The color changes in this painting are extremely subtle; the transition from light blue to dark blue is almost imperceptible.

As the negotiation reached a critical stage, the tone of both sides became subtle, and neither was willing to concede first.

She smiled somewhat subtly, as if she knew some inside information but it wasn't convenient to say it directly.