Wernette, P.; Thompson, S.; Eyler, R.; Taylor, H.; Taube, C.; Medlin, A.; Decuir, C., and Houser, C., 2018. Defining dunes: Evaluating how dune feature definitions affect dune interpretations from remote sensing.Coastal resiliency is the ability of a beach–dune system to recover to a previous state after a storm, and this resiliency is affected by prestorm beach and dune morphology and storm climate (i.e. storm frequency and intensity). Improvements in remote sensing technology such as LIDAR and structure from motion have enabled rapid collection and production of digital elevation models used to assess storm impact and recovery. Although rapid poststorm assessment requires a consistent approach for extracting dune morphology, relatively little attention has focused on defining the different parts of a dune. The goals of this paper are to examine how the definition of a dune feature drives the methodology used to extract dunes and to synthesize a comprehensive definition of dune features. An analysis of existing approaches for extracting beach and dune morphology demonstrates that there is considerable variation in how the beach–dune transition (i.e. dune toe) is defined. Many definitions are recursive or include ambiguous terminology, resulting in a dune toe or crest line position dependent on user interpretation of the definition. Other definitions rely heavily on user interpretation of dune features at varying stages in the feature extraction process. Reliance on visual interpretation can result in substantially different feature locations across different interpreters. Given the impact of varying definitions on dune resiliency assessments and legal implications for dune features location, this study proposes a series of semantic models for dune features. Semantic modelling of coastal morphology is vital for consistently and accurately assessing coastal recovery and predicting future coastal assessments on the basis of a consistent set of criteria.