Based on the dictionary, peanut is countable. Just consult any online dictionary you can find in the internet: You will see the plural from of peanut is peanuts. The reason is maybe we can still see the peanut seed not like powder (as in flour or sand), not like grain (as in rice or wheat).
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countable
countable
The noun 'hill' is a countable noun. The plural form is 'hills'.
cookies are countable unless you have brain problems
countable
Shark is a countable noun.
Prawn - prawns is the plural - is a countable noun
Duck as an animal is countable, but if you mean the meat it is uncountable.
Countable
countable
few is countable
The word hair can be both a countable noun and a non countable noun, depending on how it is used. For example in the sentence "Mary has long blonde hair", it is non countable. In the sentence "Dad is getting a few gray hairs" it is countable.