subtilize
To make subtle; to make thin or fine; to make less gross or coarse.
transitive
To refine; to spin into niceties.
transitive
Nor as yet have we subtilized ourselves into savages.
To use subtle arguments or distinctions.
intransitive
Where it comes from
From French subtiliser; equivalent to subtle + -ize.
Adapted from the Wiktionary entry subtilize (CC BY-SA 4.0).