Grammar is different from phonology and vocabulary (see below Semantics), 
though the word grammar is often used comprehensively to cover all aspects of 
language structure.In the case of dead languages, known with 
certainty only in their written forms, this must necessarily be done; insofar as the 
somewhat different grammar of their spoken forms made use of sound features not 
represented in writing (e.g., stress differences), this can, at best, only be inferred 
or reconstructed.