Often he went to sleep on it, as he was, without undressing, without sheets, wrapped in his old student’s overcoat, with his head on one little pillow, under which he heaped up all the linen he had, clean and dirty, by way of a bolster.
There are no more uses of "bolster" in the book.
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So I’d grabbed a book for myself and propped up a row of pillows for Mia to bolster her leg against, like she liked to at night.
Gayle Forman -- Where She Went
But I am bolstered by Liv Crawford, whom I haven’t actually seen in some time but whose daily contact with me is most regular, in the form of a different catered box dinner delivered each afternoon by her new assistant, Julie, a cheery, bouncy young woman whose talk and dress are uncannily like Liv’s.