1. Bio­di­ver­sity con­ser­va­tion poli­cies incor­po­rat­ing a no net loss (NNL) prin­ci­ple are being imple­mented in many coun­tries. How­ever, there are lin­guis­tic and con­cep­tual incon­sis­ten­cies in the use of terms under­ly­ing these NNL policies.
2. We iden­tify incon­sis­ten­cies that emerge in the usage of eight key terms and phrases asso­ci­ated with NNL poli­cies: bio­di­ver­sity, frames of ref­er­ence (i.e. base­lines, coun­ter­fac­tu­als), no net loss, mit­i­ga­tion hier­ar­chy, bio­di­ver­sity off­set, in-kind/out-of-kind, direct/indirect and mul­ti­pli­ers.
3. For each term, we make rec­om­men­da­tions to sup­port con­cep­tual con­ver­gence, reduce ambi­gu­ity and improve clar­ity in com­mu­ni­ca­tion and pol­icy doc­u­men­ta­tion. How­ever, we also warn of the chal­lenges in achiev­ing con­ver­gence, espe­cially given the lin­guis­tic incon­sis­ten­cies in sev­eral of these key con­cepts among coun­tries in which NNL poli­cies are employed.
4. Pol­icy impli­ca­tions. The rec­om­men­da­tions made in this arti­cle, on improv­ing clar­ity and sup­port­ing con­ver­gence on key no net loss (NNL) con­cepts, should help elim­i­nate ambi­gu­ity in pol­icy doc­u­men­ta­tion. This is cru­cial if pol­i­cy­mak­ers are to design robust poli­cies that are (i) trans­par­ent, (ii) trans­lat­able into prac­tice in a con­sis­tent man­ner and (iii) suf­fi­ciently under­stood and sup­ported by stake­hold­ers to be effec­tive in practice.