Definition of effectualness in English:

effectualness

noun

See effectual

‘Once the effectualness of these principles is realized, it's hard to fathom working any other way, and it's really very simple.’
‘It's been proven by numerous patients for years but late analyses have disputed the effectualness of these drugs.’

Pronunciation

effectualness

/ɪˈfɛktʃʊəlnəs/