• xore group,
• vore group,
• fore group,
• dore group,
• cire group,
• ckre group,
• clre group,
• cpre group,
• c0re group,
• c9re group,
• coee group,
• code group,
• cofe group,
• cote group,
• co5e group,
• co4e group,
• corw group,
• cors group,
• cord group,
• corr group

The adjective form of the word "core group" is "core" itself.

The plural form of the word "core group" is "core groups".

The singular form of the word "core group" is "core group". The word remains the same in both singular and plural forms.