รู้ดี

Explanation

รู้ดี combines รู้ (“to know” or “to understand”) with ดี used adverbially to mean “well” or “fully.” Here, ดี does not mean “good.” A particularly common pattern is รู้ดีว่า followed by a clause. It means “to know full well that…” and often stresses clear awareness of a reality, risk, consequence, or another person's intention. It can also take an explicit topic, as in รู้เรื่องนี้ดี (“to know this matter well”). The expression is neutral and natural in both conversation and writing.

Usage

It is commonly used when someone is fully aware of a reality, the circumstances of a problem, the risks or consequences of an action, or another person's intentions. Patterns such as ฉันรู้ดีว่า… (“I know full well that…”) and คุณรู้ดีว่า… (“You know very well that…”) often occur in explanations, arguments, and warnings.

Caution

For being acquainted with a person or knowing someone well, Thai normally uses รู้จัก + person + ดี; for example, รู้จักเขาดี means “to know him well.” The expression ทำเป็นรู้ดี means “to act like a know-it-all.” This negative meaning comes from the construction with ทำเป็น (“to pretend or act as if”), rather than being a separate meaning of รู้ดี by itself.

1 know full well synonyms

• รู้ชัดเจน

  รู้ชัดเจน emphasizes that one's knowledge is clear and unambiguous. รู้ดี more naturally conveys being fully aware or knowing something well across a wider range of contexts.

• เข้าใจดี

  เข้าใจดี focuses on understanding an idea, reason, process, or feeling well. รู้ดี is broader and can also mean being fully aware of a fact or situation.