The lustfulness in his eyes made people uncomfortable.

lustfulness 是由形容词 lustful（充满欲望的）加上名词后缀 -ness 构成的名词。lust 本意是"强烈的欲望"，常特指"性欲"。 lustfulness 指"充满欲望的状态或特质"，通常带有贬义，表示过度或不恰当的欲望。