Learn how to say Cruxes correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word crux:
Word forms: plural cruxes, cruces (ˈkruːsiːz Pronunciation for )
a vital or decisive stage, point, etc (often in the phrase the crux of the matter)
a baffling problem or difficulty
(mountaineering) the most difficult and often decisive part of a climb or pitch
a rare word for cross
C18: from Latin: cross