Denshi Jisho — Online Japanese dictionary

開く あく 1: to open (e.g. doors);
2: to open (e.g. business, etc.);
3: to be empty;
4: to be vacant; to be available; to be free;
5: to be open (e.g. neckline, etc.);
6: to have been opened (of one's eyes, mouth, etc.);
7: to come to an end;
8: () to open (one's eyes, mouth, etc.);
9: () to have a hole; to form a gap; to have an interval (between events)
Common word, Godan verb with ku ending, Intransitive verb 
開く ひらく 1: to open (e.g. a bank-account, festival, etc.);
2: () to spread out; to open up (flower bud, umbrella, etc.); to widen (gap, distance, width);
3: to hold; to give (party, conference, etc.)
Common word, Godan verb with ku ending, Transitive verb 

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