Difference between peculiar and unique

Business English Lesson, Advanced Level

ESL/EFL Test #175 [color=blue]“SKUs and Pricing”, question 1

Sales derive from a product’s stock-keeping Units (SKU), the combination of the specific quality, price, container size, colour, model, etc, and the product name.

(a) deviant
(b) discreet
© peculiar
(d) unique

Business English Lesson, Advanced Level

ESL/EFL Test #175 [color=blue]“SKUs and Pricing”, answer 1

Sales derive from a product’s stock-keeping Units (SKU), the unique combination of the specific quality, price, container size, colour, model, etc, and the product name.

Correct answer: (d) unique
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Hello,
Both "peculiar "and “unique” mean something special, what 's the difference here? Thanks!!!

F.F

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Hello, FF.

Peculiar is usually used to mean something special in an odd or strange way-- not appropriate here. He has a peculiar way of speaking.

There is, however, one post-adjectival phrase, peculiar to, which does not mean odd, but is synonymous with unique to:

The Kangaroo is peculiar to Australia.
The kangaroo is unique to Australia
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