Under the arching heavens of the afternoon swift passing, and the voices of children and women,
The many-moving sea-tides, and I saw the ships how they sail’d,
And the summer approaching with richness, and the fields all busy with labor,
And the infinite separate houses, how they all went on, each with its meals and minutia of daily usages,
And the streets how their throbbings throbb’d, and the cities pent—lo, then and there,
Falling upon them all and among them all, enveloping me with the rest,
Appear’d the cloud, appear’d the long black trail,
And I knew death, its thought, and the sacred knowledge of death.
From "When Lilacs Last in the Dooryard Bloom’d" by Walt Whitman.
What is the meaning of pent here?
Lexico says it is an adjective and another term for pent-up, means:
unable to be expressed or released.
Closely confined or held back.
And Webster:
shut up : CONFINED, REPRESSED