Yes, the word 'oaks' is a common noun, the plural form for the singular 'oak', a word for a type of tree, any oak tree anywhere.
A proper noun is the name of a specific person, place, thing, or a title; for example:
The word thousand is a common noun. Thousand is only a proper noun when it is the name of something or part of a title, such as the movie, Ten Thousand Drums (1959) or Thousand Oaks CA.
The plural of oak is oaks.
The plural form for the noun acorn is acorns.
common noun
Common
Common noun
common
Pea is a common noun, and peas is the plural...still a common noun.
A common noun.
Most definitely a common noun.
Camel is a common noun.
Th word tail is a common noun because the first letter of a proper noun is capitalized.