A Latin term meaning "The more difficult reading [is the stronger.]" A tenent of textual criticisim dating from the 18th century, based on the assumption that a scribe is more likely to err by replacing an unfamiliar word with a familiar one. The unfamiliar word may only be discovered during the collation of the text. Initially practiced as a way of determining the "original" text, scholars today warn that the 'difficult' reading should be considered in context and not automatically given precedence. It remains a useful aide to determining manuscript stemma. Also seen as Lectio difficilior potior; related to the term Lectio brevior.