English
implacableness
From implacable + -ness.
Formed from implacable + -ness
Latin plācō ‘to assuage, pacify, placate’
Latin plācābilis ‘placable’
Latin implācābilis ‘unappeasable, implacable’
Old French implacable ‘harsh, unrelenting’
Middle English implācāble ‘immitigable, unappeasable’
English implacable
Today it means
noun The quality of being implacable.
Language periods are conventional ranges, not dates for this word.
Etymograph / implacableness