<![CDATA[This study aimed to examine the extent to which students’ vocabulary mastery improved after being taught using DeepL Translator and to determine the significance of its effect on the vocabulary mastery of eleventh-grade students at SMAN 6 Kediri. This study employed a quantitative approach with a pre-experimental one-group pre-test and post-test design. The population consisted of 432 eleventh-grade students, with one class consisting of 36 students selected through simple random sampling as the sample. The research instrument was a vocabulary test consisting of 25 multiple-choice items administered as a pre-test and post-test. The treatment involved the use of DeepL Translator in vocabulary learning activities. The data were analyzed using descriptive statistics, the Shapiro–Wilk normality test, and a paired-samples t-test with a significance level of 0.05. The results showed that the students’ mean score increased from 77.00 in the pre-test to 85.22 in the post-test, indicating an improvement of 8.22 points. The paired-samples t-test yielded a significance value of 0.000, which was lower than 0.05, indicating a statistically significant difference between the pre-test and post-test scores. The findings suggest that the guided use of DeepL Translator can support vocabulary learning by providing contextualized translation and alternative word choices, particularly in developing students’ understanding of word meaning, contextual meaning, and appropriate word use.]]>
