A dog; the Arabic word, also the star Sirius (Kalb al-Akbar).
Literally: the heart (spiritual)
The heart — not the physical organ but the spiritual centre of perception, the seat of faith, love and the knowledge of God, the faculty by which the unseen is grasped. Sufi psychology makes the polished qalb the mirror of the Divine. Iqbal exalts the heart's intuitive vision and love above the calculating intellect, treating it as the organ through which the self touches reality and is drawn toward God.
Kalb in Iqbal’s couplets
Sukoot-e-laala-o-gul se kalaam paida kar
Tera dil to hai sanam-aashna tujhe kya milega namaz mein
Daryaon ke dil jis se dahel jaayein wo toofan
Par nahin taaqat-e-parvaaz magar rakhti hai
Hosh-o-khirad shikar kar qalb-o-nazar shikar kar
Aa ik naya shiwala is des mein bana den
Sag
A dog; often used in humble self-deprecation as 'sag-e-dar', the dog at the beloved's door.
Dil
Heart — the seat of love, vision and the living self.
Ishq
Love — passionate, all-consuming love, whether for the divine or the human.
Kashf
Unveiling; the mystic disclosure of hidden realities to the purified heart.
Aql
Intellect, reason; the calculating, analytical mind.