摘要：Vocabulary is an essential component of language proficiency which provides the basis for learners’ performance in other skills. This study investigated the effect of three kinds of definition conditions, that is L1, L2, and L1 L2 on incidental vocabulary knowledge of EFL learners. To this aim, three experimental and one control groups took part in the current study so as to examine the effectiveness of definitions with 96 target words through listening. The participants were 74 fourth-grade high school students. Eight stories with each with 12 target words (total 96 words) were given to the learners. Participants in each group listened to eight short stories under one of the three mentioned conditions for experimental groups, with no definition offered for control group. They all answered vocabulary list, eight immediate post-tests and eight delayed posttests of vocabulary. The data were analyzed using t-tests and one-way ANOVA for both immediate and delayed post-tests. The results indicated that definition groups significantly outperformed the other group in terms of vocabulary acquisition on both immediate and delayed retention of target words. However, the findings showed a significant loss from the immediate to the delayed post-tests. These findings are discussed and implications are offered for foreign language syllabus designers and instructors.
