Proto-Indo-European Roots

Root/Stem: *(s)uper, *(s)upo
Meanings:  above, under
Hellenic Greek huper 'above', hupo 'under, down'
Italic Latin super 'above'
Celtic Common Celtic *wer 'over' >
Old Welsh & Old Breton guor, Breton voar, oar, Gaulish ver-, Old Irish for, Irish Gaelic ar, Scottish air 'on, over'
Indic Sanskrit upa 'up, towards'
Iranian Avestan & Old Persian upa 'towards', Old Persian upari 'up, upwards'
Germanic Gothic uf 'under', ufar, ufaro 'above', Old English of 'of, out of', ofer 'over, above'
Notes: This root can rarely be found in dictionaries, because denoted an auxiliary part of speech, not a noun nor a verb. But it is really interesting, especially bearing in mind the *s- which is found in Greek and Italic only. The number of cognates proves it was common Indo-European.