What is the difference between "空く", "開通する", "散開星団", "公開市場操作"?

"空く" means "to open, to be vacant, to be available, to become empty", "開通する" means "to open (for traffic), to be completed (e.g., a tunnel, bridge, line)", "散開星団" means "Open cluster", "公開市場操作" means "Open Market Operations".

Quadruple VS

Synonym Boundary: "空く", "開通する", "散開星団", "公開市場操作"

All represent the core concept "open", but require precise selection.

Japanese Option A

空く

あく (aku)

N4 / CEFR

Japanese Option B

開通する

かいつうする (kaitsū suru)

N3 / CEFR

Japanese Option C

散開星団

さんかいせいだん (sankaiseidan)

C2 / CEFR

Japanese Option D

公開市場操作

こうかいしじょうそうさ (koukaishijousousa)

C2 / CEFR

Quadruple VS Nuance Contrast & Social Differences

When expressing "open" in Japanese, you must carefully distinguish between "空く", "開通する", "散開星団", "公開市場操作" based on context.

空く (あく (aku) - Level: N4): Maps to "to open, to be vacant, to be available, to become empty" and is used when An intransitive verb. Refers to something becoming empty, available, or a space opening up. For example, 席が空く.
開通する (かいつうする (kaitsū suru) - Level: N3): Maps to "to open (for traffic), to be completed (e.g., a tunnel, bridge, line)" and is used when Used for infrastructure like roads, railways, tunnels, or new services becoming available for public use. It's an intransitive verb..
散開星団 (さんかいせいだん (sankaiseidan) - Level: C2): Maps to "Open cluster" and is used when Essential structural term in CEFR C2 vocabulary syllabus..
公開市場操作 (こうかいしじょうそうさ (koukaishijousousa) - Level: C2): Maps to "Open Market Operations" and is used when Essential structural term in CEFR C2 vocabulary syllabus..

Mixing these up can easily lead to unnatural translations. Refer to the bilingual context cards below to master the boundaries!

Context for "空く"

会議室が空いていますか。

Is the meeting room available?

Context for "開通する"

新しい高速道路が来月開通する予定だ。

The new highway is scheduled to open next month.

Context for "散開星団"

私は散開星団に興味があります。

I am interested in Open cluster.

Context for "公開市場操作"

私は公開市場操作に興味があります。

I am interested in Open Market Operations.

Synonym Mastery Challenge

Which Japanese word perfectly fits this blank space?

Fill in the blank: "会議室が空いていますか。" (Meaning: "Is the meeting room available?")

🎉 Correct Answer!

Remember: "空く" is correct here because it represents "to open, to be vacant, to be available, to become empty" in the context: "Is the meeting room available?".