Mystery Number Two: Abhi to Main Jawaan Hoon

Oh, I am going to get a rightful smack on the back of my head for asking such stupid questions. But here goes.

Song: Abhi to Main Jawaan Hoon
Year: ?
Lyricist: Hafeez Jalandhari

Written by the author of Pakistan's national anthem, most memorably sung by a singer from the court of the last Maharajah of Kashmir, this is not a song to be trifled with. It is full of complex ideas and metaphors (so Amar is told), and also so many difficult and uncommon words that Amar isn't even sure whether they are urdu or farsi.

Sample couplet:
nah gham kashood-o-bast ka, buland ka nah past ka
nah bood ka nah hast ka, nah vaadaa-e-alast ka

This is not a man short on vocabulary. So what confuses Amar is the small matter of this verse:
ummid aur yaas gum, havaas gum qayaas gum
nazar sey aas-paas gum, hamaa, bajuz gilaas gum

What's 'gilaas'? Surely at the end of this couplet, towards the end of his poem, Hafeez didn't scratch his head and decide to suddenly go colloquial, and call a 'glass' 'gilaas'? To do that is completely out of character from the rest of the poem.

He certainly doesn't use gilaas anywhere else in the poem, peferring to talk of pyaalas instead.

So question one, why would a writer who prefers (in these ignorant eyes at least) to use 'pure' and literary urdu and farsi suddenly switch to a colloquialism borrowed from english? Is it not a damn odd word to be there? Or does gilaas not mean glass at all, but mean something else completely? If so, what?