Ethnobotanical research provides ample justification for comparing diverse biological nomenclatures and exploring ways that retain alternative naming practices. However, how (and whether) comparison of nomenclatures is possible remains a subject of discussion. The comparison of diverse nomenclatural practices introduces a suite of epistemic and ontological difficulties and considerations. Different nomenclatures may depend on whether the communities using them rely on formalized naming conventions; cultural or spiritual valuations; or worldviews. Because of this, some argue that the different naming practices may not be comparable if the ontological commitments employed differ. Comparisons between different nomenclatures cannot assume that either the naming practices or the object to which these names are intended to apply identifies some universally agreed upon object of interest. Investigating this suite of philosophical problems, I explore the role grey nomenclatures play in classification. ‘Grey nomenclatures’ are defined as those that employ names that are either intentionally or accidentally non-Linnaean. The classification of the lichen thallus (a symbiont) has been classified outside the Linnaean system by botanists relying on the International Code of Nomenclature for algae, fungi, and plants (ICN). But, I argue, the use of grey names is not isolated and does not occur exclusively within institutionalized naming practices. I suggest, ‘grey names’ also aptly describe nomenclatures employed by indigenous communities such as the Samí of Northern Finmark, the Sherpa of Nepal, and the Okanagan First Nations. I pay particular attention to how naming practices are employed in these communities; what ontological commitments they hold; for what purposes are these names used; and what anchors the community’s nomenclatural practices. Exploring the history of lichen naming and early ethnolichenological research, I then investigate the stakes that must be considered for any attempt to preserve, retain, integrate, or compare the knowledge contained in both academically formalized grey names and indigenous nomenclatures in a way that preserves their source-specific informational content.