A·lem·bert 
(ăl′əm-bâr, ä-läɴ-bĕr), Jean Le Rond d' 1717-1783.
(ăl′əm-bâr, ä-läɴ-bĕr), Jean Le Rond d' 1717-1783. French mathematician and philosopher who wrote the influential Treatise of Dynamics (1743). He also contributed to Diderot's Encyclopédie.