According to tantric texts the term pashu comes from the root pash, "to bind." The pashu is the man who is bound by the bonds (the pasha).
Kularnava Tantra enurnerates eight of those– pity, ignorance and delusion, fear, shame, disgust, family, custom, and caste.
So the pashu is a worldly man, seen in ignorance and bondage, as opposed to the yogi and the tattva-jnani. But it is seen that one can move between being binded or to free itself.
Shwetashwatara Upanishad in 1.8 says:
संयुक्तमेतत् क्षरमक्षरं च
व्यक्ताव्यक्तं भरते विश्वमीशः ।
अनीशश्चात्मा बध्यते भोक्तृ-
भावाज् ज्ञात्वा देवं मुच्यते सर्वपाशैः ॥ ८॥
The Lord, Isa, supports all this which has been joined together−the perishable and the imperishable, the manifest, the effect and the unmanifest, the cause. The same Lord, the Supreme Self, devoid of Lordship, becomes bound because of assuming the attitude of the enjoyer. The Jiva again realizes the Supreme Self and is freed from all Pashas.
So, the Supreme Lord binds himself (in the Pãshas) and becomes Pashu/Jeeva because of assuming the attitude of enjoyer. That Jeeva/Pashu again is freed from Pashas on realizing the Supreme Self. It is the Leela of the Lord.
To which Kularnava Tantra adds:
The body itself is the temple. The jiva itself is God Sadashiva. Do away with the faded petals of Ignorance and worship with the Consciousness of 'He am I ' . Jiva is Shiva; Shiva is jiva; the jiva pure is Shiva. When in bonds it is jiva; freed from bonds it is Sadashiva. Enclosed in husk it is paddy; freed from husk it is rice. Enclosed in karma it is jiva; freed from karma it is Sadashiva.
So,the import of the above passage is that, all bonded Jivas are Pashus but when they are free from the bondage (Pasha), then they are none other than the supreme Sadashiva himself.