Which term describes something lacking sophistication or good taste?

The term that best describes something lacking sophistication or good taste is "vulgar." This word is often used to refer to things that are crude, unrefined, or offensive, particularly in terms of behavior, speech, or style. In contrast to more elevated or tasteful qualities, vulgarity denotes a lack of discernment, refinement, or appropriateness.

Words like "elegant," "refined," and "classy" imply a degree of sophistication, tastefulness, and quality. Elegant suggests grace and beauty, refined indicates a polished or sophisticated nature, and classy refers to a stylish demeanor or appearance. Therefore, these terms stand in opposition to the idea of lacking sophistication or good taste, making "vulgar" the most suitable choice for describing something that falls short in those areas.