1.AdverbAs a matter of supposition; in the beliefs or according to the claims of some people.
"People from other planets have supposedly visited Earth in flying saucers.; According to your testimony, you were supposedly at home watching TV when the murder occurred."
2.AdverbUsed in place of "supposed to be," often in informal or colloquial speech, as a mispronunciation.
"My parents told me I am supposedly in bed by 10 P.M."