Great for next time you want somebody to choose where to eat, perhaps!
Literally: attach – harmony – thunder/lightning – same
Alternately: Having no thoughts or opinions of one’s own. Bonelessly going along with whatever other people around you are doing. The meaning of always following others instead of having one’s own opinion is actually contained within 付和; the 雷同 simply emphasizes the meaning by adding the image of things trembling in response to a thunderclap.
Notes: 付 may be replaced with 附 without any change in meaning or pronunciation. (Homophonous substitutions 不和 or 雷動, however, are incorrect.) Also, the first and second halves of the compound may switch places, although this is much less common.
The origins of this compound can supposedly be traced back to the Book of Rites, a 9th-century text that gained prominence in the Confucian canon.