brainwave vs apprehension

brainwave and apprehension both are nouns.

Word	Noun	Adjective	Verb	Adverb
brainwave	Yes	No	No	No
apprehension	Yes	No	No	No

As nouns, apprehension is a hypernym of brainwave; that is, apprehension is a word with a broader meaning than brainwave:

brainwave: the clear (and often sudden) understanding of a complex situation
apprehension: the cognitive condition of someone who understands

Other hypernyms of brainwave include discernment, savvy, understanding.

brainwave (noun)	apprehension (noun)
the clear (and often sudden) understanding of a complex situation	the act of apprehending (especially apprehending a criminal)
(neurophysiology) rapid fluctuations of voltage between parts of the cerebral cortex that are detectable with an electroencephalograph	the cognitive condition of someone who understands
	painful expectation
	fearful expectation or anticipation