From the Latin sub, meaning “from below,” and ponere, meaning “to place.” Together, to place under.
“Supposed to”: To place or be placed under an expectation or assumption. Said expectation would take the infinitive form, e.g. to be, to make, to do.
“Suppose”: To place something/someone under an assumption.
Question: Is the weight I feel today caused exclusively by the bacon pizza I ate at 2am?