'upward-sloping' is a Modern English compound formed from 'upward' + 'slope' + the present-participle suffix '-ing' (i.e., 'upward' + 'sloping'), where 'upward' indicates direction toward a higher position and 'slope' denotes a slanted surface or incline.

'upward' comes from Old English 'upweard' (from 'up' + suffix '-weard' meaning 'toward, in the direction of'); 'slope' entered English via Middle English 'slope'/'slop(e)', ultimately from Germanic sources (cognates in Old Norse and other Germanic languages) meaning 'a slant or incline'. These elements combined in Modern English to form descriptive compounds like 'upward-sloping'.

Individually, 'upward' originally meant 'toward the top' and 'slope' meant 'an inclined surface'; combined as 'upward-sloping' the compound preserves these senses, describing something that inclines toward a higher point (the meaning has been largely compositional and stable).