noun, masculine/ˈexe/plural: ejes
axis; axle; shaft, spindle; core, heart, center (main idea); hub (center of activity)
“El eje principal es el comercio de derechos de emisión.” — The main focus is on emissions trading.
Inherited from Old Spanish exe, ex, ax, inherited from Latin axem, from Proto-Indo-European *h₂eḱs- (“axis”). First attested in the 13th century. Cognate with English axis. Compare Catalan eix, Portuguese eixo.