1. To lecture or to give advice on morality or behavior in an irritatingly tedious or overbearing way: "When the mother of the teenagers started to preachify to them, they tended to tune her out and pay no attention to what she was saying."
2. To moralize or to speak as if delivering a sermon; to express moral judgments: "`Mary's counselor at the university was considered to be a bit old fashioned and was often preachifying to the students' about their behavior."