What is an antonym for sassy?

There isn't one single perfect antonym for "sassy," as its meaning can vary depending on context. However, here are some options depending on the intended nuance:

For "bold" or "confident":

* Timid

* Shy

* Submissive

* Unassuming

* Hesitant

For "flippant" or "disrespectful":

* Respectful

* Polite

* Deferential

* Obedient

* Submissive

For "stylish" or "witty":

* Plain

* Bland

* Dull

* Uninspired

* Boring

The best antonym will depend on the specific context in which you are using the word "sassy."