subtle
SUT-uladjMeaning so slight or delicate that it is hard to notice
Memory hook the silent B in SUBTLE. The b in subtle makes no sound at all, so you hardly notice it is there. A difference that slight is subtle.
The soup had a subtle hint of lemon.
In context The change in the painting was subtle; only an expert noticed that one tiny boat had been moved from the left side of the harbor to the right.
Similar slight, faint, delicate, understated
Opposite obvious, blatant, glaring
From Latin subtilis, “fine, thin, precise.” The b was added to the English spelling to match the Latin and was never pronounced.