Contact and Comparison: Bah in the Malay Particle Ecology

This paper examines the Malay‐origin discourse particle bah in Brunei English, drawing on 56 written tokens from the Reddit sub‐corpus and 52 spoken tokens from the Corpus of Brunei English (CoBE). We propose system displacement to capture what happens when a discourse particle operates outside the contrastive system that sustains its pragmatic force. Cross‐register comparison reveals a gradient of displacement: in spoken data, bah retains Malay‐like positional flexibility and functional range, with directive (21.2%) and agreement (13.5%) functions well represented alongside dominant assertion (46.2%). In written CMC discourse, position narrows to clause‐final (82.1%), assertion/emphasis dominates (58.3%), solidarity functions attenuate, and new readings, particularly irony, emerge. Reported‐speech tokens ( n = 8) in which writers represent Malay interaction show bah retaining its core Malay functions, confirming that the shift is ecologically driven rather than competence‐based. The findings demonstrate that formal similarity across registers is an unreliable guide to functional equivalence.