This paper examines language used in five of the largest manosphere communities on Reddit (r/TheRedPill, r/braincels, r/MensRights, r/seduction, and r/MGTOW) to identify idiosyncratic language use within these communities. To do so, a novel methodology which combines key-key-word analysis with notions from set theory was used to identify and compare keywords between corpora and to find keywords that are used uniquely within – and thus are distinctive to – these five separate communities. The paper achieves the following: it (i) presents a novel method for identifying what we term ‘complement keywords’ (keywords that are not shared between multiple different corpora when compared against the same reference corpus), and (ii) explores idiosyncratic language use in five separate manosphere communities. The analysis first examines interdiscursive relationships between communities emerging from the complement keywords identified before discussing community-specific preoccupations emergent in the idiosyncratic language use found in these five communities.