Whereas the usual use of wa is as a conjunction (meaning 'and'), the wāw rubba is used, particularly in poetry, in an exclamatory fashion to introduce a new subject.
wa-laylin ka-mawji l-baḥri arkhā sudūlahū ʿalayya bi-anwāʿi l-humūmi li-yabtalī Many a night, like a wave of the sea, let down its curtains Upon me to test me with all sorts of cares This riddle on the touchstone likewise begins with wāw rubba, here rendered simply as 'someone':
wa-mudarraʿin min ṣibghati l-layli burdatan yufawwafu ṭawran bi-n-nuḍāri wa-yuṭlasú ʾidhā saʾalū-hu ʿan ʿawīṣayni ʾaškalá ʾajāba bi-mā ʾaʿyā l-warā wa-huwa khrasú[5] Someone covered by the fabric of night's (dark) cloak, once scratched by pure gold, then having it wiped off again.
When people ask him about two inscrutable things which appear so much alike as to cause doubt between them, his answer transcends the power of humans, but he remains mute nonetheless.
This name arises from the supposition that the wāw functions like the word rubba, and moreover that this usage originated through phrases like wa-rubba rajulin (وَرُبَّ رَجُلٍ, 'and many a man') from which the word rubba was elided.