The transfer of P from agricultural land to water attracts scientists of varied expertise. The multidisciplinary nature of factors controlling P transfer has lead to confusions in communication because of inappropriate or ambiguous use of terminology. Therefore, we have attempted to classify terminology for P transfer into: (i) processes (or modes) (e.g., erosion, leaching, incidental) (ii) pathways (e.g., overland flow, subsurface flow, drainage flow), and (iii) form terms (e.g., those that can be described in soil or water samples). A method of classifying pathways by scale, plane, and time is suggested and a particular caution is noted for leaching, which is a process, not a pathway, and runoff (a vaguely defined pathway). Current terminology for forms in water is confusing because terms such as soluble, dissolved, particulate, inorganic, and organic can be technically incorrect if used inappropriately when describing P forms involving membrane filtration and Murphy-Riley Mo-blue chemistry. We suggest an improved method for describing the forms of P in waters, which is operationally defined and states the analytical method and size of filter used.