Pent

This is the result of many years of pent up anger and frustration.

Source: tatoeba (11453360)

There was a catch in my voice, thick as it was with the pent of unshed tears; had I let them flow they would have come out forty per cent proof.

Source: wiktionary

As the old woman, with a gigantic and distorted image of herself thrown half upon the wall behind her, half upon the roof above, sat bending over the few loose bricks within which it was pent, on the damp hearth of the chimney—for there was no stove—she looked as if she were watching at some witch’s altar for a favourable token; […]

Source: wiktionary

Wherever Miss Clavering went, this infatuated young fellow continued to follow her; and being aware that his engagement to his cousin was known in the world, he was forced to make a mystery of his passion, and confine it to his own breast, so that it was so pent in there and pressed down, that it is a wonder he did not explode some day with the stormy secret, and perish collapsed after the outburst.

Source: wiktionary