Here are a few options for a WordPress post_tag description in Traditional Chinese for the title “功能物質” (Gong Neng Wu Zhi – Functional Substance), ranging from concise to slightly more explanatory, suitable for different contexts:

**Option 1: Concise**

* **Description:** 具有特定功能的物質。 (Ju You Te Ding Gong Neng De Wu Zhi. – Substances that possess specific functions.)

This is a straightforward, easy-to-understand definition.

**Option 2: Slightly More Explanatory**

* **Description:** 泛指在特定用途中發揮作用的物質，例如藥物、營養素等。 (Fan Zhi Zai Te Ding Yong Tu Zhong Fa Hui Zuo Yong De Wu Zhi, Li Ru Yao Wu, Ying Yang Su Deng. – Refers to substances that play a role in specific applications, such as medications, nutrients, etc.)

This gives examples and a bit more context.

**Option 3: Emphasis on Practical Application**

* **Description:** 用於改善健康、解決問題或實現特定目的的物質。 (Yong Yu Gai Shan Jian Kang, Jie Jue Wen Ti Huo Shi Xian Te Ding Mu De De Wu Zhi. – Substances used to improve health, solve problems, or achieve specific goals.)

This highlights the practical applications of functional substances.

**Option 4: Suitable for a Science/Medical Context**

* **Description:** 研究或應用於生物體內，具有特定生理活性或化學性質的物質。 (Yan Jiu Huo Ying Yong Yu Sheng Wu Ti Nei, Ju You Te Ding Sheng Li Huo Xing Huo Hua Xue Xing Zhi De Wu Zhi. – Substances researched or applied within organisms, possessing specific physiological activity or chemical properties.)

This is more technical, suitable for scientific or medical posts.

**Considerations When Choosing:**

* **Target Audience:** Who are you writing for? Experts or the general public?
* **Content of the Post:** What is the specific post about? Does it focus on health supplements, chemicals, food ingredients, etc.?
* **SEO:** Consider including related keywords that people might search for, like “保健品”, “營養素”, “藥物”, “活性成分”.

Regardless of the option you choose, make sure it accurately reflects the content that will be categorized under this tag. Remember to add the description within the WordPress tag settings. Good luck!