IPA: /əˈsjuːməblɪ/
KK: /ə'sjuməblɪ/
In a way that can be assumed or taken for granted; likely or probably true.
Assumably, the meeting will start at 10 AM, but we should confirm with the organizer.
Assumably is formed from "assume" (from Latin "assumere", meaning to take up or receive) and the suffix "-ably" (meaning in a manner that can be). The word means in a manner that can be taken up or accepted as true without proof.
Think of 'taking up' ('assumere') something as true, and the '-ably' means it can be done in that way. This helps you remember that 'assumably' refers to something that can be accepted as true.