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
(c) 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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