Fundamental terms in the field of ecology are ambiguous, with multiple meanings associated with them. While this could lead to confusion, discord, or even tests that violate core assumptions of a given theory or model, this ambiguity could also be a feature that allows for new knowledge creation through the interconnected nature of concepts. We approached this debate from a quantitative perspective, and investigated the cost of ambiguity related to definitions of ecological units in ecology related to the general term "community." We did a meta-analysis of tests associated with two bodies of literature, Hubbell's unified neutral theory of biodiversity and biogeography and Diamond's assembly rules, that rely on a specific ecological unit that assumes that species are existing within a local area and that they have overlapping resource needs. We predicted that if ambiguous terminology is widespread, then researchers will have tested them with many different ecological units, that in addition some of these ecological units will violate the core assumptions of the theory, and finally that the overall level of support for a theory will be stronger if appropriate ecological units were used. We found that indeed multiple different ecological units were used in the literature to test both theories, with 65 percent appropriate ecological units for neutral theory tests, and only 6 percent for assembly rule tests. Finally, there was some evidence that the support for a theory depended on whether appropriate ecological units were used for neutral tests, but there was not enough data for the assembly rule tests. These results thus show that ambiguous terminology in ecology is having measurable effects on research and is not of solely philosophical concern. We advocate that authors be explicit in their writing and outline core assumptions of theories, that researchers apply these consistently in their tests, and that readers be attentive to what is written and cognizant of their potential biases.