supposeyoudaoicibaDictYouDict[suppose 词源字典]
suppose: [14] Latin suppōnere meant literally ‘put under’ (it was a compound verb formed from the prefix sub- ‘under’ and pōnere ‘put, place’, source of English position, and its original meaning is best preserved in English suppository [14], literally ‘something placed underneath’). From it was derived the noun suppositiō, which, on the analogy of Greek hupóthesis (source of English hypothesis [16], and itself made up of elements meaning literally ‘under’ and ‘put’), came to be used for an ‘assumption’ – English gets supposition [15] from it.

This meaning then fed back into the verb, which English acquired via Old French supposer.
=> position, suppository[suppose etymology, suppose origin, 英语词源]
suppose (v.)youdaoicibaDictYouDict
early 14c., "to assume as the basis of argument," from Old French suposer "to assume" (13c.), probably a replacement (influenced by Old French poser "put, place") of *suppondre, from Latin supponere "put or place under; to subordinate, make subject," from sub "under" (see sub-) + ponere "put, place" (past participle positus; see position (n.)). Meaning "to admit as possible, to believe to be true" is from 1520s.