usable

Compared meaning: ready to work or be used (adjective).

比较义项：运作的，可用的（形容词）。

• operational

  Formal word for machines, systems, or facilities that have been installed, tested, and are now functioning as intended; suggests official readiness for service, not used for small everyday objects.

  用于机器、系统或场所，指其已安装、测试完毕并正式投入运行，强调正式的可运行状态，不用于日常小物件。

  All systems are now operational and monitoring is live.

  所有系统现已正式运作，监控也已上线。

• usable 本词

  Simply means something still works or can serve its basic function, with no sense of official readiness; applies broadly, including old, damaged, or repaired everyday items.

  只是说某物仍能使用、还能实现基本功能，不带正式启用的意味，适用范围更广，包括旧的、损坏过或修好的日常物品。

  After cleaning it, the old laptop was still perfectly usable.

  清理之后，这台旧笔记本电脑依然完全可以使用。

Operational and usable both mean something is ready to use, but differ in formality. Operational is more formal, for machines, systems, or facilities that have been installed and tested, now functioning. Usable means something works or serves its function, with no sense of official readiness.

这两个词都可以表示某样东西已经能够使用，但语气不同：operational 更正式，强调设备、系统或场所经过安装、测试或修复后正式投入运行；usable 更口语化，只是说某物还能用、功能还正常，不涉及正式启用的意味。

Compared meaning: able to be used or obtained (adjective).

比较义项：可以使用的（形容词）。

• available

  Stresses that something or someone can be obtained, accessed, or is free at a given time; used for people's schedules, stock, seats, or resources, not about how well something works.

  强调某物或某人在某个时间可以获得、可以联系到或有空，多用于人的日程、库存、座位或资源，而不涉及东西好不好用。

  Tickets for the concert are still available online.

  演唱会的门票网上仍然有售，可以买到。

• usable 本词

  Stresses that something is still in working condition or good enough quality to serve its purpose, focusing on function rather than whether anyone can obtain or access it.

  强调某物仍处于可正常运作或质量足够好的状态，能发挥其用途，重点在功能本身，而不是别人能不能获得或联系到它。

  The old bicycle was rusty but still perfectly usable.

  那辆旧自行车虽然生锈了，但依然完全能用。

Both words mean something can be used, but from different angles. Available stresses something or someone can be obtained or is free now. Usable stresses something is still in working condition and functions properly. Available's other meaning, 'single, not in a relationship', is not compared.

这两个词都表示“可以使用”，但角度不同：available 强调某物／某人此刻可以获得、抽得出空，不涉及好不好用；usable 强调状态或功能仍然完好，能正常发挥作用。这里不比较 available 表示“单身、没有伴侣”的用法。