urging to some course of conduct or action; exhorting; encouraging
Latin hortātōrius encouraging, equivalent to hortā(rī) (dictionary.com)
"After about half an hour, we landed on a small island named Adele, where we were greeted by a large sign: 'Have You Checked for Rats, Mice and Seeds?" A few years ago, after an intensive campaign of poisoning and trapping, Adele was declared 'pest-free.' The arrival of a single pregnant rat could undo all that work; hence the hortatory signage."
- Elizabeth Kolbert, "The Big Kill: New Zealand's crusade to rid itself of mammals", 22 & 29 December 2014 The New Yorker