Definition of niggling for English Language Learners. : causing you to feel a slight pain or to be worried or annoyed for a long time.
What is PPAP? The Production Part Approval Process (PPAP) is a standardized process in the automotive and aerospace industries that helps manufacturers and suppliers communicate and approve production designs and processes before, during, and after manufacture.
As a summary, CPAP stands for continuous positive airway pressure. These machines blow a constant level of positive air pressure through a mask into your nose (or nose and mouth). Bilevel PAP refers to a machine that delivers two different levels, where a higher pressure is used during inhalation and a much lower pressure is given during exhalation.