Lip reading
Lip reading was the ability to discern what someone a distance away was saying by watching the movements of their lips. 

The deaf ambassador Riva could lip read. ()

In 2370, when Ensign Sam Lavelle expressed his curiosity over what Ensign Sito Jaxa and Commander William T. Riker were discussing, Ensign Taurik asked him if he'd ever considered learning how to lip read. ()

According to Kira Nerys, Shakaar Edon's mumbling while giving mission briefings resulted in the entire resistance cell having to learn to lip read. ()

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Linguistics