h₂ed
“to, near, at (proximity)”near/at
PIE preposition meaning to, near, or at in proximity. Source of Latin ad, English "at," and related spatial words.
Discussion
*h₂ed is a Proto-Indo-European preposition meaning "to," "near," or "at," expressing spatial proximity and direction toward.
Latin ad "to, toward, at" is the primary reflex, yielding the highly productive English prefix ad- (with assimilation: ac-, af-, ag-, al-, an-, ap-, ar-, as-, at-). Examples include admit, advance, advise, attract, accept, affirm, aggregate, announce, appear, arrive, and hundreds more. This is one of the most productive prefixes in English through Latin.
The initial laryngeal *h₂ colors the vowel to *a, visible in Latin ad. Germanic reflexes are debated; Old English æt "at" (modern English at) may derive from this root, though some scholars prefer a separate derivation.
Oscan ad and Umbrian ař confirm Italic attestation beyond Latin. The root expresses the basic concept of directed proximity—moving toward or being situated at a point.
The assimilation patterns of Latin ad- before consonants (ad + cedere > accedere, ad + firmāre > affirmāre) have produced English doublets where the prefix is barely recognizable. Modern descendants include English at (possibly), and through Latin: the ad- prefix in admit, advance, attract, accept, affirm, aggregate, and hundreds of others.
Notes
Source of Latin "ad" (to/near), English "at". Proximity/goal marker.