Sentence:  In 1960 , David D. Thomas published Basic Vocabulary in some Mon Khmer Languages AL 2 , no. 3 , pp. 7 - 11 ) , which compares 8 Mon-Khmer <WSD>languages</WSD> with the I-E language data on which Swadesh based the revised retention rate ( * * f ) in place of original ( * * f ) , and his revised 100 word basic glottochronological list in Towards Greater Accuracy ( IJAL 21 : 121 - 137 ) . 
Meaning of the word marked with <WSD> tags:  a systematic means of communicating by the use of sounds or conventional symbols