Assumably

adv. [f. prec. + -LY².] As may be assumed or taken for granted, presumably.

1883.  Athenæum, 12 May, 613/2. It is also, assumably, indebted to the rendering of Madame Sarah Bernhardt. Ibid., 20 Oct., 505/3. Sufferings which will assumably unfit him for future happiness.