Supple means bending easily without cracking. Supple leather, stay supple, supple limbs.
Of leather it means soft and workable, which is what conditioning is for. Of a body it means flexible, and suppleness is one of the components of fitness alongside strength and stamina. Figuratively it means adaptable: a supple mind. Note that the Latin behind it means kneeling in supplication, so a supple thing is one that bends — which is where supplicate comes from too.
1adjectivesuppleBending easily without cracking.
“Rub oil into the leather boots to keep them supple.”
supple is a quality of flexibility.
Old French souple comes from Latin supplex, kneeling or submissive, probably sub plus plicare, to bend. Supplicate and pliable come from the same bending.
Latin
supplex
Old French
souple
Middle English
souple
English, today
supple
Built from
From Middle English souple, from Old French souple, soupple (“soft, lithe, yielding”), from Latin supplex, supplex (“suppliant, submissive, kneeling”), of uncertain formation. Either from sub + plicō (“bend”) (compare complex), or from sub + plācō (“placate”). More at sub-, placate.
Etymology from Wiktionary, CC BY-SA