diff --git a/difftest/doc/rational.md b/difftest/doc/rational.md
index 81a0c2b40..292b0d130 100644
--- a/difftest/doc/rational.md
+++ b/difftest/doc/rational.md
@@ -6,7 +6,7 @@ In existing online difftest solutions, step-by-step implementations often lack g
 #### Objective
 The goal of offline difftest is to ensure the correctness of each instruction’s observed behavior during processor execution, while providing a flexible validation mechanism for handling undefined behavior. The validation process involves three steps:
 
-1. Running the driver to generate the DUT (Device Under Test) trace.
+1. Running the driver to generate the DUT (Design Under Test) trace.
 2. Using the DUT trace to generate the model trace.
 3. Detecting instruction differences by comparing the DUT trace and model trace using the difftest algorithm.