'Culture' is a word frequently invoked within medical education literature to explain challenges faced by learners in practice. While social settings and practices are widely acknowledged as critical influences on medical education, there is vast variability in how the term 'culture' is employed. This may lead to confusion, resulting in assumptions and oversights. This critical literature review aims to characterise how the term 'culture' is explicitly and implicitly conceptualised in medical education research. Four leading English language journals in the medical education field were searched in a twelve-month period for research papers or reviews that mentioned culture in title or abstract in a substantive way. A content analysis was undertaken of extracted definitions. In addition, metaphor analysis was used to identify conceptual metaphors, which were subsequently clustered thematically. Our search yielded 26 papers, 8 of which contained definitions, mostly from the organisational literature. We interpreted nine conceptual metaphors related to how the term culture was employed (terroir, divider, dominant force, toxic force, obstacle, microclimate, object, brand and holdall) in four categories (unchanging, powerful, can adapt around, can be used). This critical review reveals that medical education as a field: 1) draws most explicitly from the organisational literature; 2) invokes culture in multiple means but in ways that privilege either acontextual human agency or all-powerful social forces; and 3) regards culture as a negative or neutral force but rarely a positive one. There is a notable absence around conceptualisations of 'culture' that allow educator, student and administrator agency but at the same time acknowledge the deep forces that various social settings and practices exert. Other literatures investigating learning cultures and cultural reflexivity focus on this nexus and may provide possible means to advance considerations of culture within medical education research.