1.
to open one's mouth (to speak, yawn, or receive food, medicine, or a dental exam)
The basic, literal sense: to physically open the mouth. Commonly heard at the dentist (口を大きく開けてください), when feeding a baby or an animal, or when describing someone yawning or singing. Note: for the sense 'to start talking; to speak up', Japanese usually prefers 口を開く with the reading ひらく.
2.
to open (a bottle, package, or other container); to unseal
By extension from the 'mouth' metaphor for openings: to remove the cap or seal of a bottle, jar, bag, or similar container, often for the first time. Common with foods, drinks, cosmetics, and medicines.
The construction is noun 口 + を + verb 開ける. 口 here refers literally to the mouth (sense 1) or to the opening/mouth of a container (sense 2); 開ける is the transitive verb 'to open'.
Usage
- Sense 1 is nearly always concrete and physical. The metaphorical 'open one's mouth = start speaking' sense is normally carried by 口を開く (same kanji, but read ひらく). Beginning learners often conflate them.
- For the intransitive counterpart (a mouth/container opens by itself or is open), use 口が開く or the state form 口が開いている.
- In sense 2, 口を切る is a near-synonym, especially for unsealing a new package or bottle for the very first time.
Common collocations
- 口を大きく開ける: to open one's mouth wide
- 口を開けて笑う: to open one's mouth and laugh
- あくびをして口を開ける: to open one's mouth in a yawn
- ワインの口を開ける: to open a bottle of wine
- 瓶の口を開ける: to open the mouth of a bottle
- 袋の口を開ける: to open the mouth of a bag
Similar words
- 口を開く: to open one's mouth (and speak); to break one's silence — figurative use, focused on speech.
- 口を切る: to be the first to speak; also to unseal a new container — overlaps with sense 2 when referring to opening something for the first time.
- 口を閉じる / 閉める: to close one's mouth — the antonym.
- 開ける: to open — the general transitive verb; combines freely with many objects (door, window, box).
Related Words
Antonym:
閉める (to close one's mouth)