The New Fowler's Modern English Usage, Revised Edition

azure | azure 84
nounced /ai/ and is normally spelt aye, azure. This 14c. loanword from French
esp. in parliamentary language (The ayes has fluctuated in pronunciation in the
have it), in nautical language in Aye, aye, last two centuries between /'ae3(j)ua/,
sir (the correct reply on board ship on I'se&l (OED, 1885, Daniel Jones, 1917, but
receipt of an order), and in some northern
dialects in Britain, esp. in Scotland and l'ei-1 (given as a variant in OED and
both cite other pronunciations as well),
{Are you coming? Aye, I'm on my way). Jones). The initial sound is now usually
2 The word meaning 'ever' was first /ae-/ not /ei-/, and the medial consonant
recorded C1200 in the Ormulum, and is [-Z-] or /-3-/, while the final sound varies
derived from ON et, ey (cognate with OE markedly between /aua/ rhyming with
â), used in the same sense. It is normally pure /pjua/ (the dominant pronunciation)
pronounced /ei/ and spelt aye.
and /-a/.
3 The spelling ay is occasionally used
for both senses.