Much discussion of meaning by philosophers over the last 300 years has been predicated on a Cartesian first-person authority (i.e. ‘infallibilism’) with respect to what one’s terms mean. However this has problems making sense of the way the meanings of scientific terms develop, an increase in scientific knowledge over and above scientists’ ability to quantify over new entities. Although a recent conspicuous embrace of rigid designation has broken up traditional meaning-infallibilism to some extent, this new dimension to the meaning of terms such as ‘water’ is yet to receive a principled epistemological undergirding (beyond the deliverances of ‘intuition’ with respect to certain somewhat unusual possible worlds). Charles Peirce’s distinctive, naturalistic philosophy of language is mined to provide a more thoroughly fallibilist, and thus more realist, approach to meaning, with the requisite epistemology. Both his pragmatism and his triadic account of representation, it is argued, produce an original approach to meaning, analysing it in processual rather than objectual terms, and opening a distinction between ‘meaning for us’, the meaning a term has at any given time for any given community and ‘meaning simpliciter’, the way use of a given term develops over time (often due to a posteriori input from the world which is unable to be anticipated in advance). This account provocatively undermines a certain distinction between ‘semantics’ and ‘ontology’ which is often taken for granted in discussions of realism.