h₁eǵʰs
“out of, from within”out/from
PIE preposition meaning out of or from within. Source of Latin ex, English "out," and Greek ek/ex.
Discussion
*h₁eǵʰs is a Proto-Indo-European preposition meaning "out of" or "from within," expressing motion from interior to exterior.
Latin ex "out of, from" is the primary reflex, yielding the enormously productive English prefix ex- (exit, export, exclude, expect, experience, explain, express, extend, external, and hundreds more). The assimilated form e- appears before certain consonants (emit, evade, event). Greek ek/ex "out of" gives ec-/ex- in English (ecstasy, eclipse, eccentric, exodus).
Old Irish ess- "out" and Welsh eh- continue the Celtic form. Lithuanian iš "out of" and Old Church Slavonic iz "from" confirm Balto-Slavic attestation. The initial laryngeal *h₁ produces e-vocalism.
In Germanic, the root is not directly preserved as a preposition (replaced by *ut- "out"), though some scholars connect it to certain compound forms. The palatovelar *ǵʰ is confirmed by the satem reflexes.
The root expresses the fundamental spatial concept of emergence or extraction—moving out from within. Modern descendants include English the ex- prefix (exit, export, exclude, express, extend, external, experience), and through Greek: ecstasy, eclipse, eccentric, and exodus.
Notes
Source of Latin "ex" (out of), English "out" via Germanic. Exiting/emergence.