The story
From centaur + -ism, due to centaurs having two limbs (their arms) in the front raised from the ground not used for locomotion.
Etymology from Wiktionary, CC BY-SA 4.0.
centaurism
Today it means: The evolution of a creature with multiple pairs of legs evolving to give rise to a descendant where the frontmost pair of legs is raised from the ground, no longer being used in locomotion and freeing them up for other activities. Full definition →