The school of thought that owes allegiance to Ludwig Wittgenstein teaches that language conditions perceptions. When we use the term ‘cytotoxic T lymphocyte’ or ‘helper Tcell’ we tend to orientate our own thinking processes, and those of listeners or readers, down particular paths. Part of the problem is that we are often describing cell populations by functions that may either be a property of only a proportion of those that are being assayed, or are simply inferred from the expression of various cell–surface markers. The consequence can be a measure of confusion that might be avoided if we could communicate with greater clarity. Is it possible to achieve a better terminology that will be accepted generally? The following are some examples of why there may be some value in thinking about this.