European.
...European powers... European is the adjective, modifying the word powers; but it should be capitalized.
Proper adjective
No, European is an adjective, the corresponding proper noun is Europe.
The adjective form of America is American. The word American can also be a noun (demonym).
European.
The correct way to form the compound adjective for "European" with the prefix "pro" would be "pro-European."
...European powers... European is the adjective, modifying the word powers; but it should be capitalized.
Proper adjective
European
No, European is an adjective, the corresponding proper noun is Europe.
pro-European
The proper adjective form is European. (It is also the demonym for a person from Europe.)
The proper adjective for a person, thing, or characteristic is European (capitalized).
The adjective form of America is American. The word American can also be a noun (demonym).
The class visited the City Cultural Center to see the European historical clothing display.
Yes, it is proper to capitalize the word "European" when referring to people, languages, or things related to Europe. However, when used in a general sense or as an adjective, it does not need to be capitalized (e.g., European culture vs. a European country).