Synonyms of the word 
STAID → DECOROUS - SEDATE
staid
- adj. Serious, organized, and professional; sober.
- adj. Always fixed in the same location; stationary.
- v. Obsolete spelling of stayed.
decorous
- adj. Marked by proper behavior.
sedate
- adj. in a composed and temperate state.
- v. to tranquilize by giving a sedative; to calm; to soothe; to induce sleep.
If you are interested in words, visit the following sites :
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- 1word.ws/staid to play with words, suffixs, prefixs, etc.