say it: SUHT-uh-lee
subtly is an adverb meaning "in a subtle manner". It carries one recorded sense.
in a subtle manner
“late nineteenth-century French opera at its most beautiful, subtly romantic with a twilight melancholy”
Definitions, synonyms and semantic relations for subtly come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.