time-server

noun

1. a person who shapes his or her conduct to conform to the opinions of the time or of persons in power, especially for selfish ends.

noun

1. a person who compromises and changes his or her opinions, way of life, etc, to suit the current fashions

n.1580s, from expression serve the time “shape one’s views to what is in favor” (1550s), translating Latin tempori servire. See time (n.) + serve (v.).