Vase
Vase (vās or vaz; 277) , noun
[French vase; compare Sp. & Italian vaso; from Latin vas, vasum. Compare Vascular, Vessel.]
Until the time of Walker (1791), vase was made to rhyme with base, case, etc., and it is still commonly so pronounced in the United States. Walker made it to rhyme with phrase, maze, etc. Of modern English practice, Mr. A. J. Ellis (1874) says: “Vase has four pronunciations in English: vaz, which I most commonly say, is going out of use, vaz I hear most frequently, vāz very rarely, and vās I only know from Cull's marking. On the analogy of case, however, it should be the regular sound.”
The Merriam-Webster's 10th Colletgiate Dictionary says: “U. S. oftenest vās; Canada usu. and U. S. also vāz; Canada also & U. S. sometimes vaz.”
One wit has noted that “a vaz is a vāz that costs more than $100.”, suggesting that the former is considered a higher-class pronunciation.