difficile
Hard to work with; stubborn.
obsolete
Difficult.
obsolete
[…] forasmuch as he was to judge of an internall beauty, of a difficile knowledge, and abstruse discovery.
Where it comes from
From late Old French difficile, from Latin difficilis, from dis- + facilis (“easy”).
Adapted from the Wiktionary entry difficile (CC BY-SA 4.0).