n̥dʰo
“in, within, inside”under/within
PIE preposition meaning in, within, or inside. Related to spatial terms for interior position.
Discussion
*n̥dʰo is a Proto-Indo-European preposition meaning "in," "within," or "inside," expressing interiority and internal position.
The root is closely related to *h₁en "in" and *h₁enter "between," forming part of the PIE system for expressing spatial containment. Latin endo- (archaic form of in) and Greek éndov "within" preserve the root in compound formations.
The syllabic nasal *n̥ gives different reflexes across branches: Germanic *un- or *in-, Latin en-/in-. The relationship to *n̥dʰer- "under" is debated—some scholars see *n̥dʰo as a shorter form of the same root, while others treat them as distinct but related formations.
Old Irish and- "in it" and related Celtic forms may continue this root. The Balto-Slavic evidence is limited and debated.
As a spatial term, *n̥dʰo expresses the concept of being enclosed or contained within a space, complementing *h₁en (general "in") and *h₁enter ("between/among"). The PIE prepositional system distinguished these nuances of interiority with precision that is partially lost in most daughter languages, where *h₁en typically absorbed the functions of *n̥dʰo.
Notes
Source of Latin "endo/indo", English "endo-". Interior locative.