ichidan verb

開 [开] kāi

adjective | verb
: to open; to start; to turn on
: to boil
: to write out (a prescription, check, invoice etc)
: to operate (vehicle)

開く | あく aku

godan verb with ku ending | intransitive verb
: to open (e.g. doors)
: to open (e.g. business)
: to be empty
: to be vacant; to be available; to be free
: to be open (e.g. neckline)
: to have been opened (of one’s eyes, mouth)
: to come to an end
: () to open (one’s eyes, mouth)
: () to have a hole; to form a gap; to have an interval (between events)

開き | ひらき hiraki

noun
: opening; gap
: (Suffix) dried and opened fish

開く | ひらく hiraku

godan verb with ku ending | transitive verb
: to open (e.g. a bank-account, festival)
: () to spread out; to open up (flower bud, umbrella, etc.); to widen (gap, distance, width)
: to hold; to give (party, conference)

開ける | あける akeru

ichidan verb | transitive verb
: to open (a door, etc.); to unwrap (e.g. parcel, package)
: to open (for business)
: to empty; to clear out; to make space; to make room
: () to dawn; to grow light
: to end

開ける | ひらける hirakeru

ichidan verb | transitive verb
: to become opened up; to improve; to get better;
: to develop; to progress; to become civilized (civilised); to be up-to-date;
: to be enlightened; to be sensible

開かる | はだかる hidakaru

godan verb with ru ending | intransitive verb
: (Usually written using kana alone) to be separated; to be exposed; to be wide open
: to stand with one’s limbs apart (blocking the way)

開ける | はだける hidakeru

ichidan verb | transitive verb
:(Usually written using kana alone) to open; to bare; to expose
: to stretch