batch = B = Batman factor

bathtub curve n.

Common term for the curve (resembling an end-to-end section of one of those claw-footed antique bathtubs) that describes the expected failure rate of electronics with time: initially high, dropping to near 0 for most of the system's lifetime, then rising again as it `tires out'. See also burn-in period, infant mortality.

--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.