Can be pronounced either /banvee'ver/ or /bonveevoeur/*
Bon viveur is very close in meaning to bon vivant. Viveur means "a living person", while vivant translates as "is living". It is generally translated as 'he who lives well'. A bon viveur is someone who enjoys life, and lives it fully. This often implies a classy but hedonistic lifestyle, especially in referring to someone who enjoys good food and drink.
Plural can be either bons viveurs or bon viveurs.
* 'oeu', in this case, is a diphthong that I do not know the HTML for. It is the vowel sound in boeuf, if that helps.