cisplain verb cis•plain | \sis’plān\ cisplained; cisplaining Definition transitive + intransitive of a cisgender person :to explain something related to the topic of gender or to the experience of being transgender to a transgender person in a condescending way that assumes they have no or incorrect knowledge about the topic. // So Karen then cisplains to me why I’m lucky to be born without a uterus. // I really didn’t appreciate your Boomer dad cisplaining to me why being trans is a choice.