crux

Everyday

1. The most important or difficult part of a problem, question or argument: «The crux of the matter is that we don't have enough money». tree →
2. (climbing) The hardest move or section on a climbing route. tree →
3. (astronomy) Crux, the Southern Cross: a small, bright group of stars seen in the southern sky, shown on the flags of Australia and New Zealand. tree →

In the lessons

In essays, debates and maths problems, the crux is the key point you must sort out first. In geography and science for children in Australia and NZ, the Southern Cross (Crux) helps find south at night. Phrases: «the crux of the matter», «the crux of the problem», «the crux of the argument».

Examples

• The crux of the problem is that the bridge is too short. tree →
• Let's get to the crux of the argument. tree →
• The crux of the story is whether the dragon will forgive the knight. tree →
• The crux of the climb was a tricky overhang. tree →
• On the flags of Australia and New Zealand you can see the Southern Cross, called Crux. tree →
• Working out what the question asks is the crux of most maths problems. tree →

Note

Usually «the crux of» + something. Plural rare: cruxes (normal) or cruces (Latin). Comes from Latin «crux», meaning «cross». A slightly formal word; in speech, say «the main point» or «the key thing».