second shift

Short definition from Wiktionary

Noun

1. 1
   A regularly scheduled period of work, being the second one in the standard working day of any particular company: usually in the afternoon through evening; often the second of three (with 24/3 = 8 hours long), and often from 4:00 p.m. to midnight; sometimes the second of two, and sometimes with other time values.
2. 2
   A group of workers who work during this time slot.