Definitions
defence
defense
noun
1. The act of defending against attack.
Thesaurus: protection, safeguarding, preservation, security, guardianship, inoculation; Antonym: offence, aggression.
2. The method, means or equipment used to guard or protect against attack or when attacked.
3. The armed forces of a country.
4. Fortifications.
Form: defences
5. A person's answer to an accusation, justifying or denying what they have been accused of.
Thesaurus: justification, vindication, apology, excuse, explanation, extenuation.
6. law.
In a court: the person or people on trial and the lawyer or lawyers acting for them.
Form: the defence
7. sport.
The players in a team whose main task is to prevent their opponents from scoring.
Form: the defence
Derivative: defenceless
adj
Without protection; vulnerable
Thesaurus: vulnerable, endangered, exposed, helpless, naked, wide open, powerless, unarmed; Antonym: protected.
Derivative: defencelessly
adverb
Derivative: defencelessness
noun
Etymology: 13c: from Latin defendere, defensum to defend.
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defense defence
Just to add to the confusion