say it: SUHT-uhl
subtle is an adjective meaning "difficult to detect or grasp by the mind or analyze". It carries 3 recorded senses.
difficult to detect or grasp by the mind or analyze
“his whole attitude had undergone a subtle change”
“a subtle difference”
“that elusive thing the soul”
working or spreading in a hidden and usually injurious way
“glaucoma is an insidious disease”
“a subtle poison”
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for subtle 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.