Correct spelling, explanation: the difference between defence and defense is primarily a matter of regional spelling variations – they are the same word spelled differently. Defence is the British English spelling, while defense is the American English spelling. Both spellings are correct in their respective regions, so you can use either form based on the preferred spelling conventions of the English you are using.

Definition of defence:
Noun, the act of protecting someone or something against attack or criticism
The fortress was equipped with strong walls and a sophisticated defence system to protect the kingdom from potential invaders.
The lawyer presented a compelling defence argument in court, emphasizing the lack of evidence against the accused.

Collocations with defence:
Some most commonly used collocations include:
1. National defence: the military measures and resources a country uses to protect itself.
The government increased spending on national defence to enhance the security of the nation.
2. Self-defense: the act of protecting oneself from harm or danger.
She took a self-defense class to learn how to protect herself in case of an emergency.
3. Defence mechanism: a psychological strategy used by an individual to cope with stress or protect the ego.
His tendency to make jokes in uncomfortable situations was seen as a defence mechanism.
4. Defence attorney/lawyer: a legal professional who represents a person accused of a crime.
The defence attorney presented strong evidence to challenge the prosecution’s case.

Correct spelling, explanation: the primary difference between defense and defence lies in the spelling conventions based on regional variations of English. The first one is associated with American English and the other one is associated with British English and some other varieties of English. Apart from the spelling, there is no difference in meaning between defense and defence. They both refer to the act of protecting or defending and can be used interchangeably based on the English variant you are using.