Immelodious is an adjective that describes something that is lacking melody or harmony. Synonyms for immelodious could include things like discordant, cacophonous, disharmonious, jarring, inharmonic, unmelodious, harsh, grating, jangling, and off-key. These words all convey the same general idea of a sound that is unpleasant or unpleasant to listen to. Immelodious might be used to describe a person's singing voice or a piece of music that doesn't quite hit the right notes. It could also be used in a more metaphorical sense, such as to describe a conversation that isn't going smoothly or a situation in which things just don't seem to be coming together.