• archeology,
• Arkology,
• arghology,
• arckology,
• arcaoology,
• arciology,
• arkalogy,
• arkaology

• archangel,
• astrology,
• archduke,
• archaeological,
• archaeologist,
• architecture,
• archeology,
• archaeology,
• ecology.

The adjective form of the word "arcology" is "arcological".

The plural form of "arcology" is "arcologies".

The singular form of the word "arcology" is "arcology". The word doesn't change when going from singular to plural.