The Proto-Indo-European word *hₐed
Word *hₐed
Meaning to, at
See also Proto-Indo-European: *hₐed-bʰer- ‘sacrifice’
Synonyms *ad-, *h₁epi~h₁opi, *do~de

Comments
Mallory J.P. and Adams D. (2006)

Other words that might be of interest
*pro ‘away, forward, ahead’