A metaphor is a figure of speech that compares two different things to help explain an idea or concept. The term 'metaphoric source of support' can be summed up as a metaphor used to provide emotional or moral support. The crossword solution for this term is 'coattail, ' which is a metaphor for riding on the success of someone else. This phrase implies that one person is relying on the accomplishments of another to achieve their own goals.