1. superlative form of musty; having the strongest stale, stuffy, or moldy smell
Usage: superlative degree
2. superlative form of musty; most old-fashioned or outdated in style or ideas
Usage: superlative degree; figurative

Examples

• The mussiest corner of the basement had not been opened in decades.
• That old library book had the mussiest smell I'd ever encountered.
• His mussiest ideas about technology made him seem completely out of touch.
• The attic was the mussiest room in the entire house.
• She wrinkled her nose at the mussiest odor coming from the closed trunk.
• His mussiest arguments were rejected by the modern committee.