h₂epi
“at, near, before”before/at
PIE preposition meaning at, near, or before. Source of Latin apud and spatial terms for proximity.
Discussion
*h₂epi is a Proto-Indo-European preposition meaning "at," "near," or "before," used for spatial proximity and surface contact.
Latin apud "at, near, by" is the most direct reflex. Greek epí "upon, at, near" gives the prefix epi- in English (epitome, epidemic, epilogue, episode, epitaph, epigenetics). The initial laryngeal *h₂ is lost in Greek with compensatory vowel coloring.
Sanskrit ápi "also, near" preserves the adverbial use. Germanic reflexes are debated, but Old English æfter "after" may contain this root in a compound formation.
The semantic core is proximity and surface contact—being at, on, or near something. Greek extended this to "upon," giving the productive epi- prefix its characteristic meaning of "on top of" or "in addition to."
As a grammatical particle, *h₂epi was part of the PIE system of spatial prepositions that also included *h₂ep- "away from," *h₂epo "off/behind," and *h₂ed "to/at." These formed a coherent spatial framework.
Modern descendants are primarily through the Greek epi- prefix: epidemic, epilogue, epitome, episode, epitaph, epoch, and epigenetics.
Notes
Source of Latin "apud", Greek "epí" (upon). Temporal and spatial proximity.