se·date 1 
(sĭ-dāt)
(sĭ-dāt)adj.
Serenely deliberate, composed, and dignified in character or manner.
[Latin sēdātus, past participle of sēdāre, to settle, calm; see sed- in the Appendix of Indo-European roots.]
se·dately adv.
se·dateness n.