The letter C/Q has few synonyms, as it is a unique character in the English alphabet. However, there are certain words that could be used in place of C or Q in certain contexts. For instance, "cold" could be used instead of "chilly" or "cool", which are other synonyms for the word "cold". Similarly, "quoit" could be used as a synonym for "ring", which is the shape of the letter Q. Other synonyms for the letter C could include "circle", "cycle" or "curvature". While these words are not direct synonyms for C/Q, they convey the same essence and can be used interchangeably in some phrases.