Widely attested in both creole and non-creole languages of the Atlantic basin, the function word o has
been traditionally described as a ‘sentence/phrase final particle’, owing to its typical syntactic behaviour, rather than to its multiple
grammatical meanings. Based on the corpus-driven analysis of the NaijaSynCor, a ~400K words corpus of spoken Naijá (i.e., Nigerian Pidgin),
this study suggests that sentence-final o can be better described as an ‘illocutionary force indicator’ whose main
pragmatic function is to modify the illocutionary force associated with directive and assertive speech acts. The study also provides
evidence for the emergence of new coordinating and subordinating functions of o in intra-sentential position that are
semantically harmonic with its assertive (i.e. epistemic) meaning in sentence-final position. The corpus-driven analysis further shows that
the higher occurrence of sentence-final o in (formal and informal) dialogic texts in comparison to monologic texts is a
reflex of its basic illocutionary function.