The word "unseemliest" means the most inappropriate or improper. Some antonyms for this word could include: proper, suitable, decent, fitting, acceptable, respectable, appropriate, becoming, fitting, and seemly. These words describe actions, behaviors, or appearances that are appropriate or acceptable in a particular situation. For example, appropriate behavior in a formal setting should be respectable, suitable, and fitting. Seemly attire for a job interview would be something appropriate and becoming. Therefore, using these antonyms can help to describe actions or behaviors that are appropriate in a particular setting or situation.