The purpose of this study was twofold: (a) to assess the retention of two word types (synonyms and homonyms) in the short term memory, and (b) to investigate the effect of these word types on word learning by asking learners to learn their Persian meanings. A total of 73 Iranian language learners studying English translation participated in the study. For the first purpose, 36 freshmen from an intact class were presented with two lists of words with their Persian meanings. One of the list included 5 pairs of synonyms and the other one included 5 pairs of homonyms. They were asked to retain as much vocabulary items as they can. Learning was measured by lexical representations of the words. The results showed that learners did better on the retention of homonyms than synonyms. For the second purpose, 37 sophomores from an intact class were provided with 40 words in pairs (20 synonyms and 20 homonyms). They were asked to write their Persian meanings in the testing session. The results indicated that students did better on learning synonyms than homonyms. The study revealed that homonyms are better retrieved in short term memory but learned more slowly regarding to the semantic representation.
