a. Obs. rare. Also 7 erron. tranquilious. [f. L. tranquill-us TRANQUIL + -OUS.] = TRANQUIL.

1

1633.  Heywood, Rape Lucrece, Wks. 1874, V. 169. He … that may live in tranquillous pleasures.

2

1656.  S. Holland, Zara (1719), 57. He was no foe to a tranquilious Subsistence.

3

  Hence † Tranquillousness (Bailey, 1727, vol. II.).

4