Leer
A leer was a lascivious facial expression.
In 2366, Lwaxana Troi described the Ferengi who had captured her and Deanna Troi, then undressed them via transporter as being "as bad as Humans. Look at the leer on his (Farek's) face." Tog then clarified that it was revulsion, adding that he did not share that emotion. (TNG: "Ménage à Troi")