Concreteness ratings are frequently used in a variety of disciplines to operationalize differences between concrete and abstract words and concepts. However, most ratings studies present items in isolation, thereby overlooking the potential polysemy of words. Consequently, ratings for polysemous words may be conflated, causing a threat to the validity of concreteness-ratings studies. This is particularly relevant to metaphorical words, which typically describe something abstract in terms of something more concrete. To investigate whether perceived concreteness ratings differ for metaphorical versus non-metaphorical word meanings, we obtained concreteness ratings for 96 English nouns from 230 participants. Results show that nouns are perceived as less concrete when a metaphorical (versus non-metaphorical) meaning is triggered. We thus recommend taking metaphoricity into account in future concreteness-ratings studies to further improve the quality and reliability of such studies, as well as the consistency of the empirical studies that rely on these ratings.