D defs.my
Entry 3 senses Webster, 1913

Subtly

/sŭt'-əl-ē/ · Sub·tly · IPA /ˈsʌt.l̩.li/
01 adv. In a subtle manner; slyly; artfully; cunningly.
  1. 1.
    In a subtle manner; slyly; artfully; cunningly.
    “Thou seest how subtly to detain thee I devise.” Milton.
  2. 2.
    Nicely; delicately.
    “In the nice bee what sense so subtly true.” Pope.
    Subtly communicating itself to my sensibilities, but evading the analysis of my mind.” Hawthorne.
  3. 3.
    Deceitfully; delusively.[Obs.]