This page contains information regarding Star Trek: Picard, and thus may contain spoilers.
The Way of Absolute Candor was the primary teaching of the Qowat Milat, an order of Romulan warrior nuns. It emphasized the total communication of emotion without filter between thought and word, resulting in the Qowat Milat being blunt and direct in conversation. The concept ran counter to everything that Romulans normally held dear. (PIC: "Absolute Candor")