Is desserts an abstract noun

Answer 1

Yes, the noun dessert is an abstract noun; a word for a concept. We think of the physical food eaten as dessert but it is a social construct that a peach or a pie is not just a food, it's a dessert.

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If you are offered or are given a dessert, it is a concrete noun (food), regardless of what it is: you can see it, touch it, smell it, taste it. The only abstraction is the time of its consumption (at the end of a meal).

The plural form is used abstractly in the metaphorical term "just desserts" - which means that a troublesome person has deservedly encountered trouble of his own.

Answer 2

No, the plural noun 'desserts' is a concrete noun, a word for the sweet course eaten at the end of meals; a word for a physical thing.