Difference between murder and assassinate

[Zorro]

Synonyms Lesson, Advanced Level

ESL/EFL Test #114 "Synonyms for kill and murder", question 10

Angela has been an informer of the mafia for many years now. She gets well paid for this dirty job but she knows that people like her do not live long. One day they the mafia itself will ......... her.

(a) assassinate
(b) liquidate
(c) slaughter
(d) execute

Synonyms Lesson, Advanced Level

ESL/EFL Test #114 "Synonyms for kill and murder", answer 10

Angela has been an informer of the mafia for many years now. She gets well paid for this dirty job but she knows that people like her do not live long. One day they the mafia itself will liquidate her.

Correct answer: (b) liquidate

Your answer was: correct
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What's the difference between:
to murder and assassinate?

When should I use "to liquidate"?
Zorro

[Mister Micawber]

.
murder: kill intentionally and with premeditation

assassinate: murder; especially of socially prominent persons

liquidate: get rid of (someone who may be a threat) by killing
.
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Native English teacher at Mister Micawber's