Dynamic EQ
An EQ band that only boosts or cuts when the signal in its frequency range crosses a threshold.
A static EQ cuts the same amount all the time. That is the wrong tool when the problem only shows up now and then — a resonance that howls on certain notes, a bass that booms on one string, a voice that turns harsh only when it pushes. Dynamic EQ gives each band a threshold, a ratio and attack and release times like a compressor, so it only intervenes when needed.
The difference from multiband compression is the shape. A multiband compressor splits the signal into adjacent bands with crossover filters and compresses each one, whereas a dynamic EQ uses ordinary EQ curves that can be narrow and sit anywhere. A de-esser is effectively a single-band dynamic EQ. Many modern EQ plugins now offer it on every band.