Background and Aim: In order to compare word definition skill between bilingual and monolingual SLI (specific language impairment), we can investigate characteristics of these children and limited processing capacity (LPC) hypothesis about SLI.

Materials and Methods: Six (7-8 years old) bilingual (Azeri- Persian) children with specific language impairment were evaluated about their word definition and then compared with 12 normal children. Impaired children were diagnosed as exhibiting a significant delay (more than one year) in language that cannot be explained by intelligence deficits, hearing loss or visual impairment. We used specific language impairment and language development tests for diagnosis and Man Whitney and Wilcox tests for analyzing data.

Result:  There is no meaningful difference between bilingual and monolingual children with SLI (p=0.394) (p=0.394).There is meaningful difference in structural aspect of definition skills (p=0.02) between Persian and Azeri language of bilingual children but in content aspect there is not significant difference (p=0.17).

Conclusion:  Findings showed that there is no meaningful difference in comparison between Bilingual and monolingual children with SLI. Therefore, LPC hypothesis about SLI is rejected.

 Keyword: Specific language impairment, Bilingualism, Monolingual, Word definition skill.