Abstract A term in one language rarely has an absolute synonymous meaning in the same language; besides, it rarely has an equivalent meaning in an L2. English synonyms of seeing and hearing are particularly grammatically and semantically different. Frame semantics is a good tool for discovering differences between synonymous words in L2 and differences between supposed L1 and L2 equivalents. Vocabulary teaching based on synonymous or bilingual equivalents has confused EFL Iranian students. Frame semantics has shown to improve L2 comprehension of EFL learners. Hence, teachers are recommended to either explain the meaning of each word or provide them with synonyms and bilingual equivalents together with complementary explanations concerning the differences between the words.