Meaning
Thirst, especially the unquenchable thirst of longing and spiritual desire in the heart.
Literally: thirst, being thirsty
Usage & notes
Tashnagi is longing imagined as a burning thirst that no draught can slake. Iqbal celebrates this unappeasable thirst of the soul, for the heart that still thirsts is still seeking, and a thirst forever renewed is the engine of the striving self.