Linguistic accuracy (LA) has been shown to be indicative of second language (L2) essay quality through the use of various measurements, such as error counts and error-free T-units. However, concerns persist regarding the precise definition of LA, as findings in recent literature often depend on the specific measures of LA employed. This study addresses this gap by using factor analysis and interviews to explore the dimensionality of LA in L2 writing assessments. The results revealed that current accuracy measures loaded onto two distinct factors, namely form accuracy and meaning accuracy, with cross-loadings observed for total errors per 100 words and the weighted clause ratio. Additionally, it was found that the quantity and type of errors differently impeded meaning comprehensibility. These findings support the bidimensionality of LA. This paper advances our understanding of the construct of LA and offers implications for L2 writing assessments and teaching.