godan ~く verb / intransitive verb:

• to open (e.g. doors) - esp. 開く
• to open (e.g. business, etc.) - esp. 開く
• to be empty - esp. 空く
• to be vacant; to be available; to be free - esp. 空く
• to be open (e.g. neckline, etc.) - esp. 明く
• to have been opened (of one's eyes, mouth, etc.) - esp. 明く
• to come to an end - esp. 明く

godan ~く verb / transitive:

• to open (one's eyes, mouth, etc.) - esp. 明く

godan ~く verb / intransitive verb:

• to have a hole; to form a gap; to have an interval (between events) ➜ 穴が開く