Zer means under/weak/defeated
Zer is also a vowel in urdu which is used below letters to indicate the sound of i.
Usually it is used in conjunction with other words, examples are given below:
zer-e-lab– in a whisper/under ones lip
zer-e-baar-obliged/thankful
zer-e-aab– under water/submerged
zer-o-zabar-topsy-turvy
Given below is a beautiful Couplet by poet Majaz which uses the word zer-e-lab.
Phir chalili hai rel isteshan se laharaati hui,
neemshab khaamoshi mein zer-e-lab gaati hui
meanings : isteshan- station, neemshab- midnight, zer-e-lab-wishpering
Zer-e-lab is also the title of a book which is a collection of letters written by Safiya Akhtar to her husband poet Jan Nisar Akhtar.
urduwallahs 
Beautiful..
Ain’t it zir-e-lab and not zer-e-lab?
Hi Boski, thanks for writing in. It is in fact ‘zer’ and not zir.
oh i dn’t knw