The nativization or phonological adaptation of words transferred from other languages can have structural-phonological consequences for the recipient language. In English, nativization of words in which the stressed vowel is spelled with the letter <a>, here called “foreign (a)” words, leads to variable outcomes, because English <a> represents not one but three phonemes. The most common outcomes historically have been /ey/ (as in potato), /æ/ (tobacco), and /ah/ (spa), but vowel choice shows diachronic, social, and regional variation, including systematic differences between major national dialects. British English uses /ah/ for long vowels and /æ/ elsewhere, American English prefers /ah/ everywhere, whereas Canadian English traditionally prefers /æ/. The Canadian pattern is now changing, with younger speakers adopting American /ah/-variants. This article presents new data on foreign (a) in Canadian English, confirming the use of /ah/ among younger speakers, but finds that some outcomes cannot be classified as either /æ/ or /ah/. A third, phonetically intermediate outcome is often observed. Acoustic analysis confirms the extraphonemic status of these outcomes, which may constitute a new low-central vowel phoneme in Canadian English.