For hours they stared relentlessly at the scarlet ribbon on the map and hated it because it would not move up high enough to encompass the city.
His head was throbbing from a shrill clamor that drilled relentlessly into both ears.
He worked himself relentlessly into exhaustion before the long night was over and came down with a snife the next day that sent him hurrying querulously into the medical tent to have his temperature taken by Gus and Wes and to obtain a mustard plaster and vaporizer.
The valve Orr was dismantling was about the size of a thumb and contained thirty-seven separate parts, excluding the casing, many of them so minute that Orr was required to pinch them tightly between the tips of his fingernails as he placed them carefully on the floor in orderly, catalogued rows, never quickening his movements or slowing them down, never tiring, never pausing in his relentless, methodical, monotonous procedure unless it was to leer at Yossarian with maniacal mischief.
There are no more uses of "relentless" in the book.